Method for improving residual defect of polycrystalline silicon

Abstract

The invention provides a method for improving residual defects of polycrystalline silicon, which comprises the following steps of: providing a chemical vapor deposition machine and a product on which a hard mask layer is to be deposited, and forming a polycrystalline silicon layer on the product; on the inner wall of a process cavity of the equal chemical vapor deposition machine and the surface of each part in the process cavity, controlling the deposition rate to form a cavity pre-deposition layer close to the film quality of the hard mask layer to be deposited; and transferring the product to a process cavity of a chemical vapor deposition machine, and then depositing a hard mask layer on the polycrystalline silicon layer on the product. An oxide layer with a low deposition rate is used as a cavity pre-deposition layer. And the residual defect of polycrystalline silicon can be effectively reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a method for improving polycrystalline silicon residual defects. Background Art

[0002] In the baseline process of depositing a polysilicon hard mask (HM) oxide layer on a chemical vapor deposition machine in the prior art, there are minute defects (polycrystalline silicon residues), and the defect map presents a special half-wafer distribution pattern (as Figure 1 shown). Existing defect data statistics show that in non-consecutive production batches, the defect rate of the first wafer in the first cassette (the first card) is significantly higher than that of other slots.

[0003] To solve the above problems, a novel method for improving polycrystalline silicon residual defects needs to be proposed. Summary of the Invention

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a method for improving polycrystalline silicon residual defects, which is used to solve the problem of minute defects (polycrystalline silicon residues) in the baseline process of depositing a polysilicon hard mask oxide layer on a chemical vapor deposition machine in the prior art.

[0005] To achieve the above purpose and other related purposes, the present invention provides a method for improving polycrystalline silicon residual defects, including:

[0006] Step 1: Provide a chemical vapor deposition machine and a product to be deposited with a hard mask layer, on which a polysilicon layer is formed;

[0007] Step 2: Control the deposition rate on the inner wall of the process chamber of the chemical vapor deposition machine and the surfaces of various components in the process chamber to form a cavity pre-deposition layer with a film quality close to that of the hard mask layer to be deposited;

[0008] Step 3: Transfer the product to the process chamber of the chemical vapor deposition machine, and then deposit a hard mask layer on the polysilicon layer thereon.

[0009] Preferably, the material of the hard mask layer in Step 1 is an oxide layer.

[0010] Preferably, the components in Step 2 include: a sealing ring, a radio frequency plasma reaction tube, a fastener, and a gas mixing chamber.

[0011] Preferably, the material of the cavity pre-deposition layer in Step 2 is an oxide layer.

[0012] Preferably, the cavity pre-deposition layer is formed at a deposition rate of 700 to for the deposition rate to form the cavity pre-deposition layer.

[0013] Preferably, in step two, the deposition rate is controlled by adjusting at least one of the gas flow rate, plasma power, deposition temperature, and pressure in the process chamber.

[0014] Preferably, the method for forming the cavity pre-deposition layer in step two includes: configuring a high-frequency or radio-frequency plasma source, generating plasma by ionizing reaction gas, and forming a silicon oxide film on the inner wall of the process chamber and the surfaces of various components in the process chamber.

[0015] Preferably, the reaction gas in step two is SiH4 and N2O or TEOS and O2.

[0016] As described above, the method for improving polysilicon residual defects of the present invention has the following beneficial effects:

[0017] The present invention uses an oxide layer with a low deposition rate as the cavity pre-deposition layer, which can effectively reduce polysilicon residual defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The defect map shown as the prior art presents a schematic diagram of a special half-wafer distribution pattern;

[0019] Figure 2 The process flow diagram shown is of the present invention;

[0020] Figure 3 The comparison diagram of the prior art and the polysilicon residual defects of the present invention shown is of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0022] Please refer to Figure 2 , the present invention provides a method for improving polysilicon residual defects, including:

[0023] Step one: Provide a chemical vapor deposition machine and a product to be deposited with a hard mask layer, and a polysilicon layer is formed on the product;

[0024] In some embodiments, the material of the hard mask layer in step one is an oxide layer.

[0025] Step 2: On the inner wall of the process chamber of the chemical vapor deposition machine and the surfaces of various components in the process chamber, control the deposition rate to form a cavity pre-deposition layer that is close to the film quality of the hard mask layer to be deposited. Since the film qualities are close, the adhesion between the hard mask layer and the cavity pre-deposition layer can be improved, and the low deposition rate can also increase the density of the cavity pre-deposition layer, thereby reducing the exfoliation of particles and improving the problem that particles (Particle) block the photoresist or etching area, resulting in the formation of residues where local polysilicon is not etched.

[0026] In some embodiments, the components in Step 2 include: a sealing ring, a radio frequency plasma reaction tube, fasteners, and a gas mixing chamber.

[0027] The sealing ring is used for the sealing of the vacuum system or gas pipelines to prevent the leakage of reaction gases or the pollution of the process chamber by external air. In low-pressure or plasma environments such as PECVD and LPCVD, the sealing performance directly affects the vacuum degree and process stability. Usually, high-temperature and corrosion-resistant elastic materials (such as fluororubber or perfluoroether) are used to adapt to the chemical reactions and temperature fluctuations in the CVD process.

[0028] In plasma-enhanced chemical vapor deposition (PECVD), the radio frequency plasma reaction tube is the connecting component between the radio frequency (RF) power supply and the reaction chamber, and is used to transfer radio frequency energy to excite the gas to form plasma. Its design affects the plasma uniformity and deposition efficiency. Usually, it is used in combination with a capacitive coupling (CCP) or inductive coupling (ICP) structure, and a dual-frequency power supply (such as 13.56 MHz high frequency + 400 kHz low frequency) can optimize the plasma stability.

[0029] Fasteners are used to fix equipment components, such as vacuum chamber flanges, gas pipeline interfaces, or heating system components, to ensure the mechanical structure stability and airtightness. They need to have heat resistance and anti-relaxation characteristics in high-temperature or vibration environments. They are commonly found in positions such as reaction chamber assembly and pump valve connection, and the materials are mostly stainless steel or corrosion-resistant alloys.

[0030] The gas mixing chamber is responsible for uniformly mixing multiple reaction gases (such as SiH4, NH3, etc.), and after ensuring the consistency of the gas ratio and distribution, it is sent into the reaction chamber. Its design affects the film composition and uniformity.

[0031] In some embodiments, the material of the cavity pre-deposition layer in Step 2 is an oxide layer.

[0032] In some embodiments, in Step 2, a deposition rate of 700 to is used to form the cavity pre-deposition layer. For example, the deposition rate can be

[0033] In some embodiments, in step two, the deposition rate is controlled by adjusting at least one of the gas flow rate, plasma power, deposition temperature, and pressure in the process chamber. By controlling the flow rate of the precursor gas (such as SiH4 / N2O or TEOS / O2), the concentration of the reactants can be controlled, thereby controlling the deposition rate; the radio frequency power is controlled to adjust the ionization efficiency, thereby controlling the reaction rate; the deposition temperature can affect the deposition rate and the film density; the pressure can adjust the gas collision frequency, thereby controlling the reaction rate.

[0034] In some embodiments, the method for forming the cavity pre-deposition layer in step two includes: configuring a high-frequency or radio frequency plasma source, generating plasma by ionizing the reaction gas, and forming a silicon oxide film on the inner wall of the process chamber and the surfaces of various components in the process chamber.

[0035] In some embodiments, the reaction gas in step two is SiH4 and N2O or TEOS and O2.

[0036] Step three: Transfer the product to the process chamber of a chemical vapor deposition machine tool, and then deposit a hard mask layer on the polysilicon layer thereon.

[0037] Please refer to Figure 3 , which shows a comparison diagram of polysilicon residual defects between the prior art and the present invention. After data verification for a period of time, using an oxide layer with a low deposition rate as the cavity pre-deposition layer can effectively reduce polysilicon residual defects.

[0038] It should be noted that the drawings provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The types, quantities, and proportions of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0039] In summary, the present invention uses an oxide layer with a low deposition rate as the cavity pre-deposition layer, which can effectively reduce polysilicon residual defects. Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0040] The above embodiments only illustrate the principles and effects of the present invention by way of example, and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A method for improving residual defects in polysilicon, characterized in that, At least including: Step 1: Provide a chemical vapor deposition machine and a product on which a hard mask layer is to be deposited, and a polysilicon layer is formed on the product; Step 2: On the inner wall of the process chamber of the chemical vapor deposition machine and the surfaces of various components in the process chamber, control the deposition rate to form a cavity pre-deposition layer whose film quality is close to that of the hard mask layer to be deposited; Step 3: Transfer the product into the process chamber of the chemical vapor deposition machine, and then deposit a hard mask layer on the polysilicon layer thereon.

2. The method for improving polycrystalline silicon residual defects according to claim 1, wherein: The material of the hard mask layer in Step 1 is an oxide layer.

3. The method for improving polysilicon residual defects according to claim 1, wherein: The components in Step 2 include: a sealing ring, a radio frequency plasma reaction tube, fasteners, and a gas mixing chamber.

4. The method for improving polysilicon residual defects according to claim 2, wherein: The material of the cavity pre-deposition layer in Step 2 is an oxide layer.

5. The method for improving polysilicon residual defects according to claim 4, wherein: In Step 2, the cavity pre-deposition layer is formed at a deposition rate of 700 to .

6. The method for improving polysilicon residual defects according to claim 5, characterized in that: In Step 2, the deposition rate is controlled by a method of adjusting at least one of gas flow rate, plasma power, deposition temperature, and pressure in the process chamber.

7. The method for improving polysilicon residual defects according to claim 5, wherein: The formation method of the cavity pre-deposition layer in Step 2 includes: configuring a high-frequency or radio frequency plasma source, generating plasma by ionizing reaction gas, and forming a silicon oxide thin film on the inner wall of the process chamber and the surfaces of various components in the process chamber.

8. The method for improving polysilicon residual defects according to claim 7, characterized in that: The reaction gas in Step 2 is SiH4 and N2O or TEOS and O2.

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