JP4055581B2 - Method for forming HSG film - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor manufacturing method and a manufacturing apparatus therefor.
[0002]
[Prior art]
With the recent miniaturization of semiconductor devices, it has become necessary to reduce the size of memory cells. However, when the memory cell is reduced, the surface area of the electrode for accumulating charges also decreases and the capacitance also decreases. Therefore, in order to increase the charge capacity of the memory cell, it is necessary to increase the surface area of the electrode of the memory cell.
[0003]
As such a method, for example, as shown in Patent Document 1, a method of increasing the surface area by making the surface of a polysilicon electrode uneven is known. Specifically, a dome-shaped (hemispherical) amorphous silicon (hereinafter referred to as an HSG film) is grown on the surface of the polysilicon electrode and formed by the following process.
[0004]
First, in the process of FIG. 7A, a P-doped a-Si film is deposited and the lower electrode is patterned.
[0005]
Next, in the process of FIG. 7B, cleaning is performed using a mixed chemical solution such as sulfuric acid and a mixed chemical solution such as aqueous ammonia to remove trace amounts of heavy metals or particles.
[0006]
Thereafter, in the process of FIG. 7C, moisture is removed by heat dehydration.
[0007]
Subsequently, in the step of FIG. 7D, the natural oxide film is removed using dilute hydrofluoric acid, and then HSG-Si is formed in the step of FIG. 7E.
[0008]
[Patent Document 1]
JP 2002-43547 A (paragraph numbers 0023 to 0033)
[0009]
[Problems to be solved by the invention]
However, in the conventional method, organic substances deposited on the film surface cannot be sufficiently removed and remain on the film.
[0010]
Since the formation of the HSG film greatly depends on the state of the underlying film, if an organic substance or the like is present on the underlying film surface, a portion where the HSG film is not formed occurs. In addition, if the organic matter remains on the film, the removal of the natural oxide film becomes insufficient, or even if the HSG film can be formed, the adhesiveness is reduced or the film is peeled off when the organic matter remains. In some cases, the yield or reliability in the manufacture of the semiconductor device decreases.
[0011]
[Means for Solving the Problems]
Therefore, in the present invention, in order to solve the above problems, a step of depositing a doped polysilicon film, a step of removing an oxide film on the doped polysilicon film, and forming an HSG film on the doped polysilicon film And a step of removing an organic substance on the doped polysilicon film after depositing the doped polysilicon film.
[0012]
As a result, organic substances on the polysilicon can be removed and the film surface can be homogenized, so that a uniform HSG film can be formed. In addition, since the adhesion of the HSG film can be improved and film peeling can be prevented, a method for manufacturing a semiconductor device with high yield and reliability can be provided.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is characterized in that the occurrence mechanism of the HSG film (rough surface silicon) formation failure is clarified and the cause is found in the organic matter remaining on the film.
[0014]
(Principle of the invention)
First, a method for forming the HSG film will be described.
[0015]
First, as shown in FIG. 5A, a BPSG film 101 (Boron Phosphosilicate glass) is deposited on the substrate 100, the capacitor electrode portion is opened, and a groove is formed.
[0016]
Next, as shown in FIG. 5B, an amorphous silicon film 102 is formed so that the capacitor electrode portion formed in the previous step is not completely embedded in the groove.
[0017]
Thereafter, the deposited amorphous silicon film 102 is subjected to a heat treatment to form the HSG film 103 with the surface of the amorphous silicon film 102 having an uneven shape (FIG. 5C), and is formed on the BPSG film 101 by etching. The HSG film 103 is removed (FIG. 5D).
[0018]
Subsequently, as shown in FIG. 5E, the BPSG film 101 is removed by dry etching to complete the HSG film 103.
[0019]
In general, the HSG film 103 is formed according to the above method. However, if an organic substance is present on the surface of the underlying film such as the BPSG film 101, the desired HSG film 103 cannot be formed. Next, the mechanism that causes the HSG film formation failure will be described.
[0020]
If the amount of organic matter adhering to the surface of the underlying film is large, the capacity of the memory cell is reduced due to defective HSG film formation. As the cause, organic matter remains. Specifically, organic substances that could not be completely removed by IPA cleaning, which is a natural oxide removal process, and organic substances that adhered to the HSG film formation process after IPA cleaning, for example, 75 minutes, This is because the surface of the polycrystalline silicon film may be covered.
[0021]
FIG. 6A is a view showing an HSG film forming chamber. In this chamber, the portion where the wafer 104 is introduced and the film is deposited is made of a quartz tube 109, and a mechanism 106 for introducing gas and a mechanism 107 for discharging gas are provided at both ends of the quartz tube 109. Here, the arrow indicates the direction in which the gas introduced into the chamber flows. Also, FIG. 6A1 shown in the lower frame shows an enlarged view of the wafer 104 introduced into the chamber. The wafer 104 introduced into the chamber is supported by the wafer holder 108, and several wafers 104 are introduced into the chamber at the same time. In this state, gas is introduced into the chamber, and an HSG film 105 is deposited on the wafer. Here, if an organic substance or the like remains on the wafer 104 during the formation of the HSG film, it becomes difficult to form the HSG in that portion. Therefore, it is necessary to remove the organic substance in advance before forming the HSG film 105. . Here, if processing is performed in a state where two or more wafers 104 are stacked, the lower wafer 104 has a higher incidence of HSG film 105 formation defects. FIG. 6B is a diagram showing a state in which the organic substance 110 remaining on the wafer 104 is removed on one side and on both sides. As shown in FIG. 6B, the organic material 110 attached to the back surface of the upper wafer 104 is transferred onto the lower wafer 104 as a cause of the higher occurrence rate of defective formation of the HSG film 105 in the lower wafer 104. It is possible.
[0022]
Here, the following three reasons can be considered to explain the relationship between the HSG formation failure and the capacity reduction of the memory cell.
[0023]
The first reason is as follows. If the organic substance 110 adheres to the underlying film before the HSG film 105 is deposited, the organic substance 110 cannot be completely removed by a normal cleaning method. ₂ ) Etc. will remain. When the upper layer wiring is formed in this state, a structure in which a natural oxide film or the like exists between the conductive films is formed, and a pseudo capacitance having an insulating film between the electrodes is generated. That is, since unnecessary capacitance is generated, the capacity of the portion that becomes the original memory cell is reduced.
[0024]
The second reason is as follows. If the organic substance 110 is present on the base film before the HSG film 105 is deposited, the HSG film 105 is not formed in that portion, so the uniformity of the HSG film 105 is lowered. Specifically, a portion where the HSG film 105 is formed and a portion where the HSG film 105 is not formed are generated. The cause is that there is no Si atom seed in the place where the organic substance 110 is present, and the Si atom is not exposed, and there is almost no seed necessary for forming an amorphous Si film. As a result, a conductive film is deposited on the laminated film of the natural oxide film and the organic material 110 layer, and unnecessary capacitance is generated, which leads to a decrease in the capacity of the memory cell.
[0025]
Finally, the third reason is as follows. The fact that the organic substance is attached on the underlying film before deposition of the HSG film 105 means that C is exposed on the film surface or that C exists at the interface between the doped polysilicon film and the amorphous silicon. means. Here, electrons are more likely to gather at C, and electrons accumulate at locations where C is on the surface or interface, so that electronic variation occurs on the film during film deposition. As a result, since the HSG film 105 is mainly deposited according to the CVD method, this electronic influence appears remarkably, making it difficult to deposit the HSG film 105 uniformly, which leads to a reduction in the capacity of the memory cell.
[0026]
Therefore, it is necessary to remove organic substances adhering to both surfaces of the wafer. There are two main removal methods: a method using wet cleaning and a method using dry cleaning.
[0027]
First, as a method for removing organic substances by wet cleaning, there is SPM (Sulfuric Acid and Hydrogen Peroxide Mixture) cleaning. However, since a chemical oxide film is formed on the surface of the silicon film, it is necessary to further remove this oxide film. Here, as a method for removing the oxide film, there is DHF (Dilute Hydrofluoric acid) cleaning, but if this method is used, the wafer surface becomes hydrophobic and a watermark may be generated. In order to suppress the generation of the watermark, it is possible to add a step of drying after washing with IPA (Isopropyl alcohole), but the number of washing steps increases. That is, a series of cleaning steps of SPM cleaning → DHF cleaning → IPA cleaning → drying is necessary, and the number of steps is increased with respect to the entire manufacturing process.
[0028]
Therefore, a method for removing organic substances by dry cleaning is effective. Specifically, UV / O _Three Washing is mentioned. UV / O _Three Cleaning means irradiating the surface of the sample with vacuum ultraviolet light to break organic bonds, and at the same time, the vacuum ultraviolet light is absorbed by oxygen to form ozone. _Three This is a method of decomposing and removing organic matter by generating active oxygen from the slag. Here, since active oxygen has a strong oxidizing power, the organic matter is oxidized and undergoes the following reaction to proceed with decomposition and removal.
[0029]
C _X N _Y + O ・ ⇒CO ₂ ↑
As a result of the reaction of active oxygen with organic matter, CO ₂ ・ NO ₂ Is generated and removed from the film surface as a gas. However, the strong oxidizing power of active oxygen also has a function to oxidize silicon on the wafer surface after removing organic substances on the wafer surface. Therefore, it is necessary to appropriately maintain the irradiation time and irradiation intensity.
[0030]
Comparing the above two methods, organic matter removal by wet cleaning may eventually generate a watermark, so organic removal by dry cleaning is more desirable. As described above, as a method for removing organic substances by dry cleaning, a method using an oxidation reaction by ozone gas as described above, a method of generating active oxygen by irradiating ultraviolet rays in an oxygen atmosphere, and a method using the oxidizing action of the active oxygen, etc. There is.
[0031]
In the present invention, by using the organic substance removing apparatus as shown in FIG. 2A, UV irradiation is performed on both surfaces of the wafer 9 using the UV irradiation unit 8, thereby preventing the generation of the watermark 9. The present invention provides a method for manufacturing a semiconductor device and an apparatus for manufacturing the same that can completely remove organic substances adhering to the substrate. Further, by adjusting the irradiation time, irradiation intensity, and the like of vacuum ultraviolet light, reoxidation of the wafer surface after removal of organic substances can be prevented. Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0032]
(First Embodiment) Organic substance removal by substrate double-sided excimer UV light irradiation
The feature of this embodiment is that the organic matter on the underlying film of the HSG film is removed by irradiating both surfaces of the wafer with excimer UV light before depositing the HSG film. Hereinafter, a specific description will be given with reference to FIG.
[0033]
First, as shown in FIG. 1A, a doped polysilicon film 2 is deposited on the surface of the wafer 1. Specifically, in a vertical reduced pressure CVD furnace, monosilane gas (SiH _Four ) And phosphine gas (PH _Three The polysilicon film to which phosphorus is added is deposited on the surface of the wafer 1 by the thermal decomposition chemical reaction (1).
[0034]
Next, as shown in FIG. 1B, the polysilicon film 2 deposited on the back surface of the wafer 1 is removed, and the surface of the wafer 1 is cleaned.
[0035]
Thereafter, as shown in FIG. 1C, the natural oxide film 3 and the organic matter 4 scattered in the previous process are deposited on the doped polysilicon film 2 before the next process. .
[0036]
Therefore, as shown in FIG. 1D, excimer UV light is irradiated on both surfaces of the wafer 1 to remove the organic matter 4 on the base film 2 of the HSG film 5. This step is a step that brings about a great effect in the present invention, and will be described in detail later.
[0037]
Subsequently, as shown in FIG. 1E, the natural oxide film 3 is removed by IPA cleaning.
[0038]
Here, the IPA cleaning is a cleaning in which the removal of the natural oxide film 3 with hydrofluoric acid (HF) and the step of drying after cleaning with IPA (isopropyl alcohole) are integrated. The removal of the natural oxide film 3 is performed in order to prevent a natural oxide film serving as an insulating film from being formed between the lower electrode of the memory cell and the HSG film 5. The reason for drying using IPA is to shorten the drying time so that the natural oxide film 3 is not formed.
[0039]
Finally, as shown in FIG. 1 (f), an HSG film 5 is deposited using the CVD method. Here, since there is no oxide film 3 or residual organic matter 4 on the underlying film of the HSG film 5, the HSG film 5 is deposited in a uniform state without causing film peeling or the like.
[0040]
Next, the organic substance removing step, which is a step that brings about the effects of the present invention, will be specifically described.
[0041]
In this step, the organic substance removing apparatus shown in FIG. This organic substance removing apparatus includes a quartz tube 11 which is a part where a wafer 9 is introduced and an organic substance is removed, and a mechanism 6 for introducing gas and a mechanism 7 for discharging gas are provided at both ends of the quartz tube 11. It has. Here, the arrow indicates the direction in which the gas introduced into the chamber flows. In addition, a plurality of excimer UV lamps 8 serving as a mechanism for irradiating light are provided above and below the quartz tube 11 into which the wafer 9 is introduced, and the portions other than the portion of the lamp 8 facing the quartz tube 11 are covered with the cover 10. ing. The wafer 9 is introduced into the quartz tube 11 from the wafer introduction port 13. Here, the wafer 9 is supported by the wafer holder 12, and a plurality of wafers can be simultaneously introduced into the quartz tube 11. Thereafter, the inside of the quartz tube 11 is depressurized using the mechanism 7 for discharging gas, and excimer UV light is irradiated to both surfaces of the plurality of wafers 9 from the excimer UV lamps 8 on both sides of the quartz tube 11.
[0042]
In the present invention, the organic matter is removed from the wafer 9 by dry cleaning using radiation ultraviolet rays (hereinafter referred to as excimer UV light) of a dielectric barrier discharge excimer lamp which is an excimer UV lamp 8 in which xenon gas is sealed. . The mechanism of organic substance removal of the present invention will be specifically described.
[0043]
First, the wavelength of excimer UV light is a center wavelength of 172 nm and the half width is 14 nm. Light having a wavelength shorter than 175 nm is directly absorbed by oxygen in the atmosphere to generate excited oxygen atoms. The 172 nm light is also ozone (O) as is the 185 nm light. _Three ) To generate atomic oxygen. Many excited oxygen atoms can be generated by these two paths. Here, the light of 172 nm has higher photon energy than the light of 185 nm, and the molecular bond of the organic substance can be easily broken. Excited oxygen atoms with very strong oxidizing power react with the cleaved molecules, and CO ₂ , H ₂ A gas such as O is formed and can be scattered and removed.
[0044]
However, since the excited oxygen atom has a very strong oxidizing power, if the excimer UV light is irradiated to the wafer 1 even after the organic matter is removed, an oxide film is generated on the surface of the wafer 1. Therefore, using pulsed irradiation at the time of irradiation is more effective because excessive oxidizing power of the generated active oxygen can be suppressed. Here, the pulse irradiation will be specifically described with reference to FIG.
[0045]
FIG. 2B shows the pressure in the quartz tube 11 (hereinafter referred to as “chamber”) where the operation for removing organic substances is performed on the vertical axis, and the recipe for the apparatus on the horizontal axis. Here, the pulse irradiation refers to irradiation in which replacement / irradiation / exhaust is one cycle and this is repeated several cycles.
[0046]
First, since the pressure in the chamber is substantially equal to the air pressure, the gas is discharged by the mechanism 7 for discharging the gas shown in FIG.
[0047]
Next, cycle 1 will be described. Here, the wafer is not yet introduced into the chamber.
[0048]
First, a small amount of oxygen and nitrogen gas is introduced into the chamber from the gas introduction mechanism 6 shown in FIG. 2A, and the pressure in the chamber is changed to be constant ((1)). Here, a small amount of oxygen gas is introduced into the chamber because the oxygen gas is an O gas necessary for the organic substance decomposition step by UV irradiation. _Three It is because it becomes the raw material of.
[0049]
Next, if the time for one cycle is 12 to 20 seconds, for example, UV irradiation for 2 seconds is performed ((2)). From the oxygen gas introduced at this time, O _Three Is formed, and active oxygen is generated, which is decomposed by reacting with organic substances remaining in the chamber.
[0050]
Thereafter, the formed organic substance-derived impurity gas is discharged from the mechanism 7 for discharging the gas shown in FIG. 2A ((3)).
[0051]
As described above, the organic substance removal cycle 1 is performed before the wafer is introduced into the chamber in order to previously remove the organic substances adhering to the chamber. If the cleanliness in the chamber is high, cycle 1 is not necessarily performed.
[0052]
Next, the wafer 9 is introduced into the chamber from the wafer introduction port 13 to remove organic substances. When the wafer 9 is introduced into the chamber, the inside of the chamber returns to a state almost equal to the air pressure again. Therefore, the inside of the chamber is again decompressed using the mechanism 7 in FIG.
[0053]
After that, cycle 2 and cycle 3 and oxygen gas replacement in the chamber (1), UV irradiation to the wafer (2), and exhaust of impurities such as reaction products (3) are repeated. Thus, organic substances adhering to the wafer are removed. In FIG. 2B, only two cycles of cycle 2 and cycle 3 are shown, but it is desirable to set the number of cycles to be repeated according to the amount of organic matter.
[0054]
Here, the irradiation process in cycle 2 and cycle 3, specifically, the pulse irradiation time will be described with reference to the drawings.
[0055]
There is a certain period suitable for the pulse irradiation time as shown in FIG. In FIG. 3A, the vertical axis represents the film thickness, and the horizontal axis represents the accumulated time. As shown in FIG. 3A, when the irradiation time is short, the film thickness remains thick and the organic matter is not sufficiently removed, but as the UV irradiation time becomes longer, the film thickness becomes thinner and the organic matter is removed. I understand. However, when a certain irradiation time is exceeded, the film thickness is increased again.
[0056]
Similarly, FIG. 3B shows the irradiation time per cycle on the horizontal axis and the film thickness of the wafer on the vertical axis. In FIG. It can be seen that the film thickness increases. This is because, when UV irradiation is performed over a certain period of time, the active substance is supplied to the wafer surface even though the organic substance has already reacted with the active oxygen and removed from the wafer. This is because it is oxidized and an oxide film is formed.
[0057]
Therefore, if the pulse irradiation time is too long, the number of unnecessary films increases. Therefore, if the pulse irradiation time is too short or too long, a desired effect cannot be obtained. In the present embodiment, the optimum time is 2 seconds. However, the value is naturally not limited to this value, and it is desirable to verify the optimum range each time.
[0058]
As described above, when pulse irradiation is performed for a suitable time, active oxygen is generated during the irradiation, and organic substances on the wafer react with the active oxygen to be decomposed and removed.
[0059]
Next, the exhaust process in cycle 2 and cycle 3 will be described. By exhausting the gas in the chamber and lowering the pressure in the chamber, a gas generated by the reaction between the organic substance and active oxygen, for example, CO ₂ , NO _X , H ₂ O or the like and active oxygen remaining in the chamber without being involved in the reaction are exhausted from the chamber.
[0060]
FIG. 4 is a graph showing the relationship between the gas replacement / gas exhaust before and after UV irradiation and the film thickness. Show. FIG. 4 shows that the film thickness of the wafer is smaller when the gas replacement in the chamber and the gas exhaust after the reaction are performed than when the gas replacement and the gas exhaust in the chamber are not performed. If the gas is not exhausted, organic matter removal is not performed accurately. Specifically, the oxidized organic matter (carbon dioxide) is decomposed again by the excimer UV light and left as residual carbon in the chamber. is there. Alternatively, the wafer surface may be reoxidized by active oxygen.
[0061]
Therefore, by performing exhaust in a certain cycle, reoxidation due to excess active oxygen can be prevented and organic substances can be removed. That is, the organic matter on the wafer can be more effectively removed by adjusting the pulse irradiation time and the gas exhaust time in the chamber.
[0062]
As described above, after the repetition of cycle 2 and cycle 3 is completed, a small amount of gas is again introduced into the chamber as shown in FIG. 2B, the wafer discharge port 14 is opened, and the pressure in the chamber is changed to air pressure. The wafer is discharged in a close state, and the organic matter removing process is completed.
[0063]
Here, regarding the next new wafer processing, whether to start from cycle 1 or cycle 2 is selected based on the cleanness of the processing environment, that is, the rule of the wiring pattern. This is because the finer the wiring pattern, the more affected by particles such as organic matter, and the higher the degree of cleanliness is required. Starting from cycle 1, since the organic substance removal step in the chamber is performed, the influence of the organic substance from the chamber itself can be prevented, and a higher cleanliness can be maintained. On the other hand, starting from cycle 2, the organic substance removal step in the chamber can be omitted, so that the wafer processing efficiency can be increased.
[0064]
As described above, in the present embodiment, the organic matter on the wafer, specifically, the underlying film of HSG can be removed by irradiating both surfaces of the wafer with excimer UV light. As a result, defects in HSG formation are reduced, and a method for manufacturing a semiconductor device that can prevent a decrease in yield can be provided.
[0065]
Second Embodiment A substrate double-sided UV irradiation device
The UV irradiation apparatus of the present invention will be described.
[0066]
As shown in FIG. 2A, this apparatus includes a quartz tube 11 which is a portion where the operation of introducing a wafer 9 and removing organic substances is performed, and a mechanism for introducing a gas to both ends of the quartz tube 11. 6 and a mechanism 7 for discharging gas. Here, the arrow indicates the direction in which the gas introduced into the chamber flows. A plurality of excimer UV lamps 8 are provided above and below the quartz tube 11 into which the wafer 9 is introduced, and the portion other than the portion of the lamp 8 facing the quartz tube 11 is covered with a cover 10. This cover is for preventing the irradiated UV light from diffusing to an unnecessary part. Further, there are a wafer inlet 13 for introducing the wafer 9 into the quartz tube 11 and a wafer outlet 14 for unloading the wafer on the opposite side. Further, the wafer 9 is supported by a wafer holding unit 12, and a plurality of wafers can be simultaneously introduced into the quartz tube 11, and the wafer holding unit 12 can also move in the vertical direction. As a result, organic substances on the wafer can be removed more uniformly.
[0067]
FIG. 2B shows a UV irradiation sequence. As described in the first embodiment, the method is a process in which replacement / irradiation / exhaust is performed as one cycle, that is, pulse irradiation is repeated several cycles.
[0068]
At this time, the organic removal amount is evaluated by comparing the film thickness before and after the excimer UV light irradiation. This is because when the organic substance is deposited on the wafer surface, the film thickness measurement result becomes thicker than the actual film thickness, so that the amount of film thickness reduced by UV irradiation can be approximately identified as the amount of organic substance removed. .
[0069]
By checking the amount of organic matter in this way, even if the amount of organic matter attached varies from wafer to wafer, the treatment can be repeated several times while adjusting the oxidizing power to remove the organic matter while preventing reoxidation of the wafer surface. I can do it.
[0070]
Further, the oxygen concentration in the chamber at the time of excimer UV light irradiation is optimally 1 to 15%, particularly around 10%. This is because when the oxygen concentration in the chamber is high, the excimer UV light is absorbed by excess oxygen and does not reach the wafer surface and the oxidation reaction is not promoted.
[0071]
Furthermore, the optimum pressure in the chamber at the time of excimer UV light irradiation is, for example, around 1.0 kPa. This is because if the pressure in the chamber is high, the excimer UV light is absorbed by excessively existing molecules in the chamber, and the excimer light does not reach the wafer surface, making it difficult to promote the oxidation reaction.
[0072]
By operating this apparatus based on the above conditions, it is possible to irradiate excimer UV light on both surfaces of the wafer and remove organic substances on the wafer surface. As a result, defective formation of the HSG film due to organic contamination is reduced, so that it is possible to provide a semiconductor device that can prevent a reduction in yield and improve reliability.
[0073]
【The invention's effect】
As described above, according to the present invention, the organic matter removal on the wafer is performed before the HSG film is formed, thereby reducing the HSG film formation failure due to the organic matter. As a result, it is possible to provide a semiconductor device that can prevent a decrease in yield and improve reliability. In addition, since organic substance removal is performed by UV irradiation, a watermark generated when the organic substance is removed by wet cleaning can be avoided, and a more uniform HSG film can be formed.
[Brief description of the drawings]
FIG. 1 is a process cross-sectional view of a first embodiment.
FIG. 2A is a cross-sectional view of the apparatus of the present invention.
(B) The figure which shows the recipe of the pulse irradiation of this invention
FIG. 3A is a diagram showing the relationship between cumulative irradiation time by pulse irradiation and film thickness.
(B) Diagram showing the relationship between irradiation time per cycle and film thickness
FIG. 4 is a diagram showing the relationship between the presence or absence of gas replacement / exhaust and the film thickness before and after irradiation.
FIG. 5 is a process cross-sectional view of general HSG film formation.
6A is a view showing an HSG film formation chamber of the present invention. FIG.
(B) Diagram showing organic transfer on the backside of the wafer
FIG. 7 is a process cross-sectional view of HSG film formation by a conventional method
[Explanation of symbols]
1 wafer
2 Doped polysilicon film
3 Natural oxide film
4 Organic matter
5 HSG film
6 Mechanism to introduce gas
7 Mechanism to discharge gas
8 UV excimer lamp
9 Wafer
10 Cover
11 Quartz tube
12 Wafer holder
13 Wafer inlet
14 Wafer outlet
100 substrates
101 BPSG membrane
102 Amorphous silicon film
103 HSG film
104 wafers
105 HSG film
106 Mechanism for introducing gas
107 Mechanism for exhausting gas
108 Wafer holding part
109 quartz tube
110 Organic matter

Claims (8)

Depositing a doped polysilicon film on the substrate;
The organic material formed on the doped polysilicon film and the organic material formed on the back surface of the substrate are stacked with a plurality of the substrates spaced apart from each other, and active oxygen is added in the presence of oxygen gas. Removing by UV irradiation to be generated ;
Removing the oxide film formed on the doped polysilicon film;
And a step of forming an HSG film on the doped polysilicon film after removing the organic substance.   2. The method of manufacturing a semiconductor device according to claim 1, wherein in the step of removing the oxide film on the doped polysilicon film, cleaning is performed using isopropyl alcohol.   2. The method of manufacturing a semiconductor device according to claim 1, wherein the UV irradiation is performed by light pulse irradiation. The step of removing the organic matter by a light pulse includes:
Among the plurality of substrates, the uppermost substrate and the lowermost substrate are subjected to UV irradiation, and the step of exhausting the impurity gas formed by the removal of the organic matter is repeated. A method for manufacturing a semiconductor device according to claim 3. 4. The method of manufacturing a semiconductor device according to claim 3, wherein in the step of removing the organic substance by the light pulse, the organic substance in the chamber is removed before the substrate is carried into the chamber for removing the organic substance. .   In the step of removing the organic material formed on the doped polysilicon film and the organic material formed on the back surface of the substrate by UV irradiation, the pressure in the chamber for removing the organic material is maintained at around 1.0 kPa. The method for manufacturing a semiconductor device according to claim 1, wherein: The semiconductor device manufacturing method according to claim 1, wherein the HSG film is simultaneously formed on a plurality of the substrates in the step of forming an HSG film on the doped polysilicon film after removing the organic substance. Method. The step of removing the organic matter by the UV irradiation includes:
Removing organic matter in the organic matter removing device before carrying the plurality of substrates into the organic matter removing device;
Carrying the plurality of substrates into the organic substance removing device;
Flowing oxygen gas into the organic substance removing device;
Among the plurality of substrates, and performing UV irradiation for the top layer of the substrate and the lowermost substrate,
The method for manufacturing a semiconductor device according to claim 1, further comprising a step of discharging an impurity gas formed by removing the organic substance in the organic substance removing apparatus.

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