Standard sheet for measuring content of boron and phosphorus and preparation method thereof

Abstract

The invention relates to a standard sheet for measuring the content of boron and phosphorus and a preparation method thereof, the standard sheet is used for calibration of an infrared spectrometric analyzer, the standard sheet comprises a substrate, and a boron-phosphorosilicate glass layer and a protective film which are sequentially stacked on the surface of the substrate, and the protective film is a silicon oxynitride film. The boron-phosphorosilicate glass can be used at high temperature or for a long time, the content of boron and phosphorus in the boron-phosphorosilicate glass is stable, the boron and phosphorus absorption peaks of the boron-phosphorosilicate glass layer are obvious, and the boron-phosphorosilicate glass can be used for calibrating an infrared spectrum analyzer.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor device detection, and in particular to a standard sheet for calibrating an infrared spectrometer to measure boron and phosphorus content and a preparation method thereof. Background Art

[0002] In the chip manufacturing industry, boro-phospho-silicate glass (BPSG) films are commonly used in interlayer dielectrics (ILDs), offering excellent planarization and filling performance. The boron (B) and phosphorus (P) content in BPSG films significantly impacts their performance. A stable B concentration effectively improves the insulation between the upper metal layer and the underlying silicon layer. Simultaneously, a stable P concentration enhances the adsorption of free ions, preventing short circuits caused by ion migration. Therefore, it is essential to measure the B (boron) and P (phosphorus) content during the BPSG film manufacturing process. Currently, this is primarily determined by irradiating semiconductor wafers with X-rays or infrared light and measuring the reflectance spectra during semiconductor manufacturing.

[0003] Infrared spectroscopy (FTIR) is a widely used technique for material composition analysis, particularly in semiconductor manufacturing for measuring the boron and phosphorus content in BPSG films. To accurately monitor the boron and phosphorus content in BPSG, BSG, and PSG films measured by FTIR, the instrument must be regularly calibrated using standard components. Traditional BPSG thin film standards are susceptible to boron (B) and phosphorus (P) precipitation after high temperatures or prolonged use, causing changes in the standard component composition and affecting measurement accuracy.

[0004] Therefore, a standard sheet with stable B (boron) and P (phosphorus) content is needed. Summary of the Invention

[0005] The technical problem to be solved by the present application is to provide a standard plate for measuring boron and phosphorus content and a preparation method thereof. The boron and phosphorus contents in the standard plate are stable even if used at high temperatures or for a long time, and can be used to calibrate an infrared spectrometer.

[0006] According to a first aspect of an embodiment of the present application, a standard plate for measuring boron and phosphorus content is provided for use in an infrared spectrometer. The standard plate includes a substrate and a borophosphosilicate glass layer and a protective film sequentially stacked on the surface of the substrate, wherein the protective film is a silicon oxynitride film.

[0007] Optionally, the protective film has a thickness of 50 nm to 80 nm.

[0008] Optionally, the substrate is a silicon substrate or a silicon carbide substrate.

[0009] Optionally, the thickness of the borophosphosilicate glass layer is 500 nm to 1000 nm, the phosphorus content in the borophosphosilicate glass layer is 5 wt % to 6 wt %, and the phosphorus content in the borophosphosilicate glass layer is greater than the boron content.

[0010] According to a second aspect of an embodiment of the present application, a method for preparing a standard sheet used in an infrared spectrum analyzer is provided, comprising: providing a substrate; Depositing a borophosphosilicate glass layer on the surface of the substrate; A silicon oxynitride film is deposited on the surface of the borophosphosilicate glass layer to prepare a stacked structure; The laminated structure is subjected to high-temperature reflow at 850° C. to 1000° C.

[0011] Optionally, the borophosphosilicate glass layer is formed by plasma enhanced chemical vapor deposition.

[0012] Optionally, depositing a borophosphosilicate glass layer on the substrate surface includes: Silicon source, boron source, phosphorus source and O2 are introduced in proportion, and a borophosphosilicate glass film of a predetermined thickness is deposited under the conditions of preset deposition temperature, working pressure and radio frequency power. The predetermined thickness is 500nm to 1000nm.

[0013] Optionally, the high-temperature reflux time is 4 hours to 8 hours.

[0014] Optionally, depositing a silicon oxynitride film on the surface of the borophosphosilicate glass layer includes: A reaction gas consisting of silane-containing gas, oxygen-containing gas and nitrogen-containing gas is introduced to form a silicon oxynitride film on the surface of the borophosphosilicate glass layer by chemical vapor deposition. The silicon oxynitride film has a thickness of 50 nm to 80 nm.

[0015] Optionally, the silane-containing gas is SiH 4 , the oxygen-containing gas is N 2 O, and the nitrogen-containing gas is NH 3 .

[0016] Compared with the prior art, the present invention has the following advantages: The present application forms a silicon oxynitride film on the surface of a borophosphosilicate glass layer. The silicon oxynitride film serves as a protective film. On the one hand, it isolates the borophosphosilicate glass layer from the external environment, prevents the borophosphosilicate glass layer from absorbing water and moisture, and prevents the precipitation of boron (B) and phosphorus (P). On the other hand, the silicon oxynitride film has a high transmittance to infrared light, and the boron and phosphorus absorption peaks of the borophosphosilicate glass layer are obvious, which will not affect the measurement accuracy of the infrared spectrometer. The standard sheet preparation method of the present application completes the formation of the borophosphosilicate glass layer and the silicon oxynitride film by two depositions, and then reflows at high temperature. On the one hand, the boron (B) and phosphorus (P) in the formed standard sheet are evenly distributed to avoid excessive concentration. On the other hand, the stress between the layers is reduced, ensuring the long-term stable use of the standard sheet. Furthermore, the preparation method avoids the formation of a silicon dioxide (SiO2) film layer in the process of forming the silicon oxynitride film layer, which interferes with the measurement of the boron (B) and phosphorus (P) content in the borophosphosilicate glass layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of a standard sheet according to an exemplary embodiment.

[0018] Figure 2 The figure is a flow chart of preparing a standard sheet according to an exemplary embodiment.

[0019] Figure 3 FIG. 4 is an FTIR absorption spectrum diagram of a standard sheet according to an exemplary embodiment.

[0020] Figure 4 This is the FTIR absorption spectrum of a standard sheet with a silicon dioxide layer on the surface.

[0021] In the figure, 11 is a substrate; 12 is a borophosphosilicate glass layer; and 13 is a silicon oxynitride film. DETAILED DESCRIPTION

[0022] Unless otherwise defined, the technical terms or scientific terms used in this specification and claims shall have the ordinary meaning understood by persons having ordinary skills in the technical field to which this application belongs. The specific embodiments of the present application will be described below in conjunction with the accompanying drawings. It should be pointed out that in the specific description of these embodiments, in order to provide a concise description, this specification cannot provide a detailed description of all the features of the actual embodiments. Without departing from the spirit and scope of this application, those skilled in the art may modify and replace the embodiments of the present application, and the resulting embodiments are also within the scope of protection of this application.

[0023] In order to solve the above technical problems, the present application provides a standard sheet for measuring boron and phosphorus content, which is used for calibration of infrared spectrometer. Figure 1In one embodiment, the standard wafer includes a substrate 11, a borophosphosilicate glass (BPSG) layer 12, and a protective film stacked sequentially on the substrate surface, wherein the protective film is a silicon oxynitride film 13. Optionally, the substrate 11 may be a silicon substrate or a silicon carbide substrate.

[0024] The present application forms a silicon oxynitride film 13 on the surface of the borophosphosilicate glass layer 12. The silicon oxynitride film 13 serves as a protective film. On the one hand, it isolates the borophosphosilicate glass layer 12 from the external environment, prevents the borophosphosilicate glass layer from absorbing water and moisture, and prevents the precipitation of boron (B) and phosphorus (P). On the other hand, the silicon oxynitride film 13 has a high transmittance to infrared light and will not affect the measurement accuracy of the infrared spectrometer.

[0025] In one embodiment, the thickness of the silicon oxynitride film 13 is between 50 nm and 80 nm. The thickness of the silicon oxynitride film 13 is determined based on the intended use of the standard film. If the thickness is too low, such as less than 50 nm, the isolation and protection provided by the borophosphosilicate glass layer 12 may be unstable over long periods of use. If the thickness is greater than 80 nm, the absorption peak of the standard film may be weak and susceptible to interference. The thickness of the silicon oxynitride film 13 can be adjusted by controlling the deposition time. Furthermore, the thickness of the silicon oxynitride film 13 should not be too thick. The thickness should be between 50 nm and 80 nm, inclusive, so that it does not affect the absorption peaks during the measurement of boron (B) and phosphorus (P) content using an infrared spectrometer, facilitating accurate measurement.

[0026] In one embodiment, the borophosphosilicate glass layer 12 has a thickness of 500 nm to 1000 nm, and the phosphorus content in the borophosphosilicate glass layer 12 is greater than the boron content. Because the phosphorus absorption peak is weaker than the boron absorption peak, the phosphorus content is greater than the boron content in the standard film, ensuring that both the phosphorus and boron absorption peaks are stably present. Specifically, the borophosphosilicate glass layer has a phosphorus content of 3 wt% to 6 wt%, such as 5 wt% to 6 wt%. The phosphorus content must ensure that the absorption peak is visible in infrared spectrometer measurements, avoiding a too low phosphorus content that results in no apparent absorption peak and unstable measurements, and avoiding a too high phosphorus content that results in excessive moisture absorption during the manufacturing process, resulting in poor stability of the fabricated borophosphosilicate glass layer 12.

[0027] According to a second aspect of the embodiment of the present application, a method for preparing a standard sheet used in an infrared spectrum analyzer is provided, which comprises: Figure 2 As shown, Providing a substrate 11, which may be a silicon substrate or a silicon carbide substrate; A borophosphosilicate glass layer 12 is deposited on the surface of the substrate 11, and the phosphorus content in the borophosphosilicate glass layer 12 can be controlled to be 5wt%-6wt%; A silicon oxynitride film 13 is deposited on the surface of the borophosphosilicate glass layer 12 to obtain a stacked structure; The laminated structure is subjected to high temperature reflow at 850°C to 1000°C.

[0028] The present invention forms a borophosphosilicate glass layer 12 and a silicon oxynitride film 13 by sequential deposition, and then uses a high-temperature reflow process to ensure the density and stability of each layer. The standard component of the present invention is manufactured using a deposition process and a high-temperature reflow process, which is easy to implement.

[0029] In one embodiment, the borophosphosilicate glass layer 12 is formed by plasma enhanced chemical vapor deposition. The borophosphosilicate glass layer is deposited on the substrate surface, including: Silicon source, boron source, phosphorus source and O2 are introduced in proportion, and a borophosphosilicate glass film of a predetermined thickness is deposited under the conditions of preset deposition temperature, working pressure and radio frequency power. The predetermined thickness is 500nm to 1000nm.

[0030] Specifically, in some examples, the precursors include tetraethoxysilane (TEOS, Si(OC2H5)4) as the silicon source, trimethyl borate (TMB, B(OCH3)3) as the boron source, and trimethyl phosphate (TMP, PO(OCH3)3) as the phosphorus source. TEOS is a liquid silicon source and needs to be atomized and delivered to the reaction chamber using a carrier gas (e.g., He).

[0031] The reaction principle for generating BPSG is: TEOS decomposes: Si is released under the action of plasma and reacts with O2 to form SiO2. TMB decomposes: B is released, which combines with O2 to form B2O3. TMP decomposes: P is released to form P2O5. The three are mixed and deposited to form BPSG film. The reaction conditions are: deposition temperature of 300℃-500℃, operating pressure of 1Torr-10Torr, and RF power of 300W-1000W. The reaction formula can be simplified as: TEOS+TMB+TMP+O2→BPSG (B2O3-P2O5-SiO2 ternary system) + by-products (volatiles) Specifically, a silicon or silicon carbide substrate is loaded into the reaction chamber of a PECVD system. The vacuum pump is then activated to reduce the chamber pressure to a high vacuum of approximately 10⁻³ Torr to eliminate interference from impurity gases in the deposition process. TEOS, TMB, TMP, and O₂ are introduced proportionally. Liquid TEOS is stably delivered via a heated evaporator and a carrier gas (such as He). The flow rates of TMB and TMP are precisely controlled. The RF power is then activated to generate a plasma and activate the decomposition of gas molecules. The deposition temperature is 400°C, the operating pressure is 8.2 Torr, and the RF power is 1000W. The BPSG film thickness is controlled by adjusting the gas flow rates and deposition time until the BPSG layer reaches the desired thickness.

[0032] In one embodiment, the silicon oxynitride film 13 is deposited on the surface of the borophosphosilicate glass layer 12, comprising: A reaction gas consisting of silane-containing gas, oxygen-containing gas and nitrogen-containing gas is introduced to form a silicon oxynitride film on the surface of the borophosphosilicate glass layer by chemical vapor deposition. The silicon oxynitride film has a thickness of 50 nm to 80 nm.

[0033] Optionally, the silane-containing gas is SiH4, the oxygen-containing gas is N2O, and the nitrogen-containing gas is NH3, or may be a mixed gas of NH3 and N2.

[0034] The reaction formula for forming silicon oxynitride film can be simplified as follows: SiH4+N2O+NH3→Si X O Y N Z + By-products (volatiles) Specifically, the laminated structure with the borophosphosilicate glass layer 12 prepared above is placed in a plasma-enhanced chemical vapor deposition chamber to deposit a silicon oxynitride film. The interval between two depositions must be kept between 5 and 8 hours. If the interval between two depositions is too long, the borophosphosilicate glass layer 12 will be unstable and prone to boron (B) and phosphorus (P) precipitation on the surface. SiH4, N2O, and NH3 are introduced proportionally. The primary silicon source, SiH4, is typically diluted with a carrier and then steadily introduced. The SiH4 and NH3 flow rates are precisely controlled. The deposition temperature is 400°C and the operating pressure is 5.75 Torr. The thickness of the silicon oxynitride film is controlled by adjusting the gas flow rates and deposition time.

[0035] In a specific embodiment, the high-temperature reflow time is 4 hours to 8 hours. After the stacked structure of the silicon oxynitride film and the borophosphosilicate glass layer 12 is formed by two depositions in this embodiment, the high-temperature reflow process is controlled to be completed within 20-25 hours to make the silicon oxynitride film and the borophosphosilicate glass layer 12 denser and more stable. The temperature of the high-temperature reflow process can be 900°C, and the reflow time can be 6 hours, which can soften and shrink the borophosphosilicate glass layer 12, making the silicon oxynitride film and the borophosphosilicate glass layer 12 dense, and ensuring the isolation and protection of the borophosphosilicate glass layer 12 by the silicon oxynitride film. This embodiment can adjust the density between the film layers and the stability of the silicon oxynitride film by controlling the temperature and time.

[0036] In one embodiment, the standard wafer after high-temperature reflow is placed in a nitrogen cabinet and stored for more than 10 days, which can increase the stability of each layer and facilitate subsequent long-term use.

[0037] A standard film was prepared using the above preparation method. Specifically, the thickness of the silicon oxynitride film 13 was 50 nm, and the phosphorus content of the borophosphosilicate glass layer was 3.367 wt% and the boron content was 1.956 wt%. The phosphorus and boron contents of the standard film were measured on different days over 50 days. The actual content was stable. On the last day, the phosphorus content was 3.365 wt% and the boron content was 1.954 wt%, showing no significant decrease. The standard film was measured using an infrared spectrometer. Figure 3 As shown, its absorption peak is obvious and there is no interference.

[0038] In a pair of comparisons, the silicon oxynitride film 13 was replaced with a SiO2 film, and the phosphorus content in the borophosphosilicate glass layer was 3.805wt% and the boron content was 2.846wt%. The structure with the silicon oxynitride film 13 was stored under the same conditions as the above-mentioned standard film and the phosphorus and boron contents were measured on different dates within 50 days. After actual measurement, the phosphorus content was 3.795wt% and the boron content was 2.791wt% on the last day. It can be seen that the boron content was significantly reduced, that is, the SiO2 film cannot ensure the stability of the phosphorus and boron contents in the structure over a long period of time. The structure was measured using an infrared spectrometer, and its spectrum is shown in FIG. Figure 4 As shown in the figure, the absorption peaks are disordered. Analysis shows that the Si-O bonds in the SiO2 film layer interfere with the Si-O bonds in the borophosphosilicate glass layer, resulting in disordered absorption peaks in the collected spectrum.

[0039] The preparation method of the present application uses two deposition and high-temperature reflux processes to ensure that no SiO2 film is formed during the preparation of the standard piece, ensuring that it can be used as a calibration piece for an infrared spectrometer.

[0040] The above description of the embodiments is intended to facilitate understanding and application of the present application by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without expending any creative effort. Therefore, the present application is not limited to the embodiments described herein, and improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope and spirit of this application are within the scope of this application.

Claims

1. A standard plate for measuring boron and phosphorus content, used in an infrared spectrometer, the standard plate comprising a substrate, a borophosphosilicate glass layer and a protective film sequentially stacked on the surface of the substrate, wherein the protective film is a silicon oxynitride film.

2. The standard sheet according to claim 1, wherein: The thickness of the protective film is 50nm to 80nm.

3. The standard sheet according to claim 1, wherein: The substrate is a silicon substrate or a silicon carbide substrate.

4. The standard sheet according to any one of claims 1 to 3, characterized in that: The thickness of the borophosphosilicate glass layer is 500 nm to 1000 nm, the phosphorus content in the borophosphosilicate glass layer is 5 wt % to 6 wt %, and the phosphorus content in the borophosphosilicate glass layer is greater than the boron content.

5. A method for preparing a standard sheet used in an infrared spectrum analyzer, characterized in that: include: providing a substrate; Depositing a borophosphosilicate glass layer on the surface of the substrate; A silicon oxynitride film is deposited on the surface of the borophosphosilicate glass layer to prepare a stacked structure; The laminated structure is subjected to high-temperature reflow at 850° C. to 1000° C.

6. The preparation method according to claim 5, wherein The borophosphosilicate glass layer is formed by plasma enhanced chemical vapor deposition.

7. The preparation method according to claim 6, wherein The step of depositing a borophosphosilicate glass layer on the substrate surface comprises: Silicon source, boron source, phosphorus source and O2 are introduced in proportion, and a borophosphosilicate glass film of a predetermined thickness is deposited under the conditions of preset deposition temperature, working pressure and radio frequency power. The predetermined thickness is 500nm to 1000nm.

8. The preparation method according to claim 7, wherein The high temperature reflux time is 4 hours to 8 hours.

9. The preparation method according to any one of claims 5 to 8, characterized in that The step of depositing a silicon oxynitride film on the surface of the borophosphosilicate glass layer comprises: A reaction gas consisting of silane-containing gas, oxygen-containing gas and nitrogen-containing gas is introduced to form a silicon oxynitride film on the surface of the borophosphosilicate glass layer by chemical vapor deposition. The silicon oxynitride film has a thickness of 50 nm to 80 nm.

10. The preparation method according to claim 9, characterized in that The silane-containing gas is SiH 4 , the oxygen-containing gas is N 2 O, and the nitrogen-containing gas is NH 3 .

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