Modification method
By exposing semiconductor substrates to controlled hydrogen peroxide gas atmospheres at low temperatures, the method addresses splashing and oxidation issues, enabling efficient polysilazane film modification into silicon dioxide for advanced semiconductor manufacturing.
Patent Information
- Application Number
- JP2024024585
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-02-21
- Publication Date
- 2025-09-02
AI Technical Summary
Existing methods for modifying polysilazane films in semiconductor manufacturing face challenges such as product defects from hydrogen peroxide solution splashing and high-temperature oxidation of non-target surfaces, which are not addressed by existing techniques like Patent Documents 1 and 2.
A method involving exposing a semiconductor substrate with a pre-processed film to a controlled atmosphere of hydrogen peroxide gas at temperatures between 50°C to 300°C, with specific gas concentration and flux, and adjusting pressure conditions to selectively modify the film without oxidizing other surfaces.
The method effectively modifies polysilazane films into silicon dioxide at low temperatures, ensuring minimal oxidation of the semiconductor substrate, facilitating high-quality insulating film formation in advanced semiconductor manufacturing.
Smart Images
Figure 2025127715000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a method for modifying a film by treating it with hydrogen peroxide gas in a manufacturing process for a semiconductor integrated circuit. [Background technology]
[0002] In general, in electronic devices such as semiconductor devices, semiconductor elements, such as transistors and resistors, arranged on a substrate must be electrically insulated, and therefore isolation structures are required between these elements to separate them.
[0003] Meanwhile, in the field of electronic devices, increasing density and integration have been progressing in recent years. This trend toward higher density and integration requires the formation of fine isolation structures that match the required integration levels. One new isolation structure that meets this need is the trench isolation structure. This structure electrically isolates elements formed on both sides of a fine trench formed on the surface of a semiconductor substrate using an insulating material filled inside the trench. This type of element isolation structure allows for a narrower area in which the isolation structure is formed than with conventional methods, making it an effective element isolation structure for achieving the high integration levels currently required.
[0004] Furthermore, when stacking elements three-dimensionally to increase density, it is necessary to provide an insulating film between layers of conductive material. Examples of such insulating films include insulating films under metal films and insulating films between metal wiring layers. Oxide films such as silicon dioxide films are often used as the insulating material for insulating films. Silicon dioxide films are formed by oxidizing the Si substrate itself, using chemical vapor deposition (CVD), or by applying an insulating material (spin-on dielectric (SOD)).
[0005] Recent advances in miniaturization have created a demand for oxide filling of fine structures, particularly those with high aspect ratios that are vertically deep or horizontally narrow. To meet this demand, the adoption of SOD, a filling method using flowable oxides, is on the rise. SOD uses a coated insulating material containing inorganic or organic components, applied by a spin-on-glass (SOG) process. This material was used in semiconductor manufacturing processes before the advent of CVD oxide films. However, because the processing technology was limited to dimensions of around 0.35 μm to 1 μm, which was not very fine, post-application modification was permitted by heat treatment at around 400°C in a nitrogen atmosphere.
[0006] However, in recent semiconductors, the minimum feature size has become smaller than 50 nm, and the use of polysilazane films as an alternative material to SOG has been considered. Polysilazane is a material obtained by the catalytic reaction of ammonia with silane compounds such as dichlorosilane or trichlorosilane. The polysilazane precursor is applied to a substrate using a spin coater when forming a thin film. During the manufacturing process, polysilazane contains impurities such as nitrogen, which originates from the ammonia. Therefore, in order to remove impurities (nitrogen and hydrogen) from polysilazane films formed using polysilazane and obtain a dense oxide film, two processes are required: modification and densification of the polysilazane film.
[0007] One method for modifying the film is, for example, to introduce water vapor into the polysilazane film in a chamber heated to about 450°C. The water vapor is taken into the polysilazane film, and the film is modified by applying heat. During this process, nitrogen and hydrogen in the film are removed and oxygen is introduced. Another method for densifying the film is to heat it to 700°C in a water atmosphere, resulting in a dense oxide film.
[0008] While polysilazane films are widely used in semiconductor manufacturing processes, there is also a growing demand for reducing the thermal load of transistors. Reasons for reducing the thermal load include preventing excessive diffusion of impurities such as boron, arsenic, and phosphorus implanted for transistor operation, preventing aggregation of metal silicides for electrodes, preventing performance fluctuations in work function metal materials for gates, and ensuring the repetitive write / read life of memory elements. In particular, semiconductor substrates contain many other films (such as silicon substrate surfaces or metal films) in addition to the polysilazane film that is the subject of film modification. Treating such semiconductor substrates at high temperatures oxidizes surfaces other than the film being treated, adversely affecting many functions. For example, oxidation of metal films can impair conductivity.
[0009] To enable the manufacture of products, semiconductor substrates must be processed at low temperatures. Plasma processing using oxidizing gases (e.g., water, oxygen, ozone, etc.) has been investigated as a method for densifying polysilazane films at low temperatures in the manufacture of silicon dioxide films using polysilazane films. Furthermore, a technique for baking polysilazane films in the presence of hydrogen peroxide has been proposed (see Patent Documents 1 and 2), but a technique for modifying polysilazane films at lower temperatures is desired.
[0010] Furthermore, instead of the conventional filling method using the CVD method, a method of filling silicon dioxide into trenches and the like using a flowable CVD method and a flowable ALD (Flowable Atomic Layer Deposition) method is also being considered. [Prior art documents] [Patent documents]
[0011] [Patent Document 1] Patent No. 5710308 [Patent Document 2] Patent No. 6381486 Summary of the Invention [Problem to be solved by the invention]
[0012] Patent Document 1 describes a method of modifying a polysilazane film in a hydrogen peroxide atmosphere by dripping an aqueous hydrogen peroxide solution onto a hot plate heated to 50 to 200°C. However, the hydrogen peroxide solution cannot be dripped into the chamber of a semiconductor manufacturing device because the dripped solution would collide with the chamber walls and splash, adhering to the semiconductor substrate and causing product defects. In addition, the pressure inside the chamber changes suddenly as the volume changes from liquid to gas, which can destabilize the processing conditions and potentially lead to product defects.
[0013] Patent Document 2 describes a method in which an aqueous hydrogen peroxide solution is heated in an evaporator, the generated hydrogen peroxide vapor is introduced into a chamber heated to 300 to 500°C, and a polysilazane film is modified at a pressure of 300 Torr or less. However, when a semiconductor substrate is treated at a high temperature, there is a risk that the surface of the Si substrate other than the film to be treated (polysilazane film) may be oxidized.
[0014] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a modification method that can selectively modify a film to be treated without oxidizing films other than the film to be treated and the surface of a semiconductor substrate. [Means for solving the problem]
[0015] In order to achieve the above object, the present invention provides the following means. [1] A modification method including a modification step in which a semiconductor substrate having a pre-processed film deposited thereon is exposed to a gas atmosphere containing hydrogen peroxide in a state in which the semiconductor substrate is held in a chamber heated to a temperature of 50°C to 300°C, thereby modifying the pre-processed film, wherein the concentration of hydrogen peroxide gas contained in the gas atmosphere is 1 to 5 vol% (volume percentage), and the gas molecular flux Γ of hydrogen peroxide in the chamber is 9.4 × 10 19 ~1.3×10 22 (pcs / (cm 2 sec)) is a modification method. [2] The modification method according to [1], wherein the pre-processed film deposited on the semiconductor substrate contains at least one of polysilazane, amorphous silicon dioxide, and silicon dioxide. [3] The modification method according to [1] or [2], characterized in that the modification step includes a step of evacuating the pressure in the chamber to 0.01 kPaA (absolute pressure) to 0.1 kPaA before introducing hydrogen peroxide gas into the chamber. [4] The modification method according to any one of [1] to [3], characterized in that the semiconductor substrate has a groove with a groove width of 5 nm or more and an aspect ratio of 100 or less, and the pre-processed film includes a portion deposited in the groove. [5] The modification method according to any one of [1] to [4], wherein the untreated film is modified into a silicon dioxide film having a refractive index of 1.45 to 1.47 by the modification step. [Effects of the Invention]
[0016] According to the present invention, it is possible to selectively modify a film to be treated without oxidizing films other than the film to be treated and the surface of the semiconductor substrate. [Brief explanation of the drawings]
[0017] [Figure 1] 1A to 1C are cross-sectional views showing an example of a method for forming an insulating film on a semiconductor substrate. [Figure 2] 1 is a cross-sectional view illustrating an example of a high aspect ratio insulating structure in a semiconductor substrate. [Figure 3] 2 is a graph showing the state of film modification in Example 1. DETAILED DESCRIPTION OF THE INVENTION
[0018] The present invention will be described below based on preferred embodiments.
[0019] The inventors of the present invention have made extensive efforts to solve the above problems, and as a result have found that, by using the following means, highly concentrated hydrogen peroxide is introduced into a chamber, and by utilizing the strong oxidizing power and reactivity of hydrogen peroxide, it is possible to modify a pre-processed film such as a polysilazane film at 300° C. or less. It has also been confirmed that the surface of a semiconductor substrate such as a silicon substrate is not oxidized at 300° C. or less.
[0020] A manufacturing method for forming an insulating film on a semiconductor substrate can be divided into the following steps, as shown in FIG. 1 : forming a film 11 on a semiconductor substrate 10 by spin coating or the like; obtaining a pre-processed film 12 by pre-baking or the like; obtaining a modified film 13 from the pre-processed film 12; and obtaining a densified insulating film from the modified film 13.
[0021] 1, (a) is a semiconductor substrate 10, (b) is a semiconductor substrate 10 having a coated film 11, (c) is a semiconductor substrate 10 having a pre-processed film 12, and (d) is a semiconductor substrate 10 having a modified film 13. The coated film 11 can be formed by spin coating, curtain coating, dip coating, or other coating methods.
[0022] The solution used for application contains a solvent capable of dissolving components such as polysilazane contained in the pre-processed film 12. Examples of the solvent include aromatic or aliphatic hydrocarbon solvents, ether solvents, and ketone solvents. At least a portion of the solvent is removed by a heating process such as pre-baking. The solvent removal process is carried out under appropriate conditions that do not cause deterioration of components such as polysilazane due to oxidation, polymerization, or the like.
[0023] The modification process is a process for obtaining a modified film 13 from a pre-processed film 12. As shown in FIG. 2, a groove 15 with a high aspect ratio may be formed on a surface 14 of a semiconductor substrate 10. The aspect ratio is the ratio (d / w) of the depth d of the groove 15 to the width w of the groove 15. A pre-processed film 12 is deposited on the surface 14 and the groove 15 of the semiconductor substrate 10. The pre-processed film 12 includes a portion 12a deposited on the surface 14 and a portion 12b deposited in the groove 15. The thickness t in FIG. 2 is the thickness of the portion 12a of the pre-processed film 12 deposited on the surface 14. The width w, depth d, and thickness t may each be uniform or may vary within their respective tolerance ranges. For example, the side surfaces of the groove 15 may be tapered, and the groove width w may vary depending on the position in the depth direction.
[0024] The above-mentioned pre-treatment film may be a film containing at least one of polysilazane, amorphous silicon dioxide, and silicon dioxide. The polysilazane film can be formed by applying a polysilazane solution. The polysilazane may be inorganic or organic. The amorphous silicon dioxide film and the silicon dioxide film can be formed by CVD or the like.
[0025] When grooves are formed in a semiconductor substrate, it is preferable that the groove width w is 5 nm or more and the aspect ratio (d / w) is 100 or less. The ratio d / w may be, for example, 40 to 200. The groove depth d may be, for example, 200 nm or more. When the pre-processing film includes a portion deposited in the groove, it is necessary to allow the hydrogen peroxide gas to penetrate into the portion inside the groove. The groove width w may be, for example, 5 to 50 nm. It is preferable that the thickness (t in FIG. 2) of the pre-processing film formed on the semiconductor substrate is in the range of 0.1 to 1 times the groove depth d.
[0026] The modification step performed in the modification method of this embodiment is a step of modifying a pre-processed film by exposing a semiconductor substrate, on which the pre-processed film has been deposited, to a gas atmosphere containing hydrogen peroxide while the semiconductor substrate is held in a chamber. The chamber is heated to a temperature of 50°C to 300°C. Examples of the processing temperature include the temperature of the chamber wall, the temperature of the gas atmosphere around the semiconductor substrate, and the temperature of the semiconductor substrate. It is preferable that these temperatures are substantially the same.
[0027] If the treatment temperature is below 50°C, the modification will not progress. A higher treatment temperature can shorten the reaction time, but the treatment must be carried out at 300°C or below to avoid adverse effects such as oxidizing films other than the film to be treated and the surface of the semiconductor substrate. To adjust the temperature inside the chamber to the treatment temperature, a process may be performed in which a gas that does not contain hydrogen peroxide is introduced into the chamber before the process in which hydrogen peroxide gas is introduced into the chamber. The temperature of the gas introduced into the chamber can be raised to the treatment temperature before it approaches the semiconductor substrate.
[0028] The chamber may be a heating furnace having walls made of a heat-resistant material such as quartz, ceramics, or glass. The chamber is preferably made of a material that does not emit components that may affect the semiconductor substrate and the unprocessed film when heated. The shape of the chamber is not particularly limited, but examples include tubular furnaces having a cross section that is circular or approximately polygonal.
[0029] The concentration of hydrogen peroxide gas contained in the gas atmosphere in the chamber is 1 to 5 vol% (volume percentage). If the concentration of hydrogen peroxide gas is less than 1 vol%, reforming does not proceed smoothly. If the concentration of hydrogen peroxide gas is 5 vol% or less, hydrogen peroxide gas is easy to generate and handle.
[0030] The gas atmosphere in the chamber may contain, in addition to hydrogen peroxide gas, a carrier gas, water vapor, etc. The concentration of water vapor is not particularly limited, but may be 1 to 25 vol%. It is preferable that the gas other than hydrogen peroxide gas and water vapor is essentially a carrier gas. Examples of the carrier gas include nitrogen gas and oxygen gas. When heat-treating a pre-treatment film that may contain organic substances, it is preferable that the concentration of oxygen gas is low, and only nitrogen gas may be used as the carrier gas.
[0031] The hydrogen peroxide gas molecular flux Γ in the chamber is 9.4×10 19 ~1.3×10 22 (pcs / (cm 2 sec)). The gas molecular flux of hydrogen peroxide is 9.4 × 10 19 (pcs / (cm 2 If the gas molecular flux Γ of hydrogen peroxide is less than 1.3 × 10 22 (pcs / (cm 2 sec) or less, it is easy to maintain the gas atmosphere containing hydrogen peroxide.
[0032] The gas molecular flux Γ represents the number of gas molecules passing through a unit cross-sectional area per unit time. The partial pressure (Pa) of hydrogen peroxide is expressed as P H2O2 , where M is the molecular weight of hydrogen peroxide (34) and T is the temperature (K), the gas molecular flux of hydrogen peroxide Γ (number / (cm 2 sec)) is (2.63 × 10 20 )×P H2O2 / √(MT), where √(MT) represents the square root of the product (MT) of M and T. The average speed of gas molecules, ν (m / sec), is calculated as (8k B T / πm), where k B Let be the Boltzmann constant, T be the temperature, π be the circumference constant, and m be the mass of the molecule.
[0033] Methods for supplying high-concentration hydrogen peroxide gas include separating hydrogen peroxide gas from an aqueous hydrogen peroxide solution using a separation membrane, vaporizing a highly concentrated aqueous hydrogen peroxide solution to generate hydrogen peroxide gas, and concentrating hydrogen peroxide vapor vaporized from a low-concentration aqueous hydrogen peroxide solution using a separation membrane. These methods can generate high-concentration hydrogen peroxide gas that is difficult to obtain by simply heating an aqueous hydrogen peroxide solution. A specific example is the Peroxidizer (registered trademark) manufactured by RASIRC, which uses the method described in Japanese Patent No. 6290856. This device generates high-concentration hydrogen peroxide gas by utilizing the effect of a separation membrane.
[0034] The pressure of the gas atmosphere in the chamber during the modification step can be set within an appropriate range. For example, it can be in the range of 10 kPaA to 100 kPaA. Here, the A in kPaA represents absolute pressure. The flow rate of the gas atmosphere containing hydrogen peroxide in the chamber is preferably in the range of 0.04 to 8.14 m / sec.
[0035] The modification step may include a step of evacuating the pressure in the chamber to 0.01 kPaA to 0.1 kPaA (absolute pressure) before introducing hydrogen peroxide gas into the chamber, thereby removing gas contained in the untreated film by evacuation and more quickly replacing it with a modification gas containing high-concentration hydrogen peroxide gas, thereby shortening the processing time.
[0036] To adjust the temperature inside the chamber to the processing temperature, a process of introducing a gas that does not contain hydrogen peroxide into the chamber before evacuating the chamber may be included, or the temperature of the chamber wall or the like may be adjusted during the process of evacuating the chamber. To adjust the pressure inside the chamber to the processing conditions, the pressure may be gradually adjusted when hydrogen peroxide gas is introduced into the chamber. Alternatively, a process of introducing a gas that does not contain hydrogen peroxide into the chamber may be included between the process of evacuating the chamber and the process of introducing hydrogen peroxide gas into the chamber. The time required for gradually adjusting the pressure can be set as appropriate, but may be, for example, within one minute.
[0037] The pre-treatment film immediately after application (after pre-baking) is a film with low density and forms a network structure that allows gas to easily penetrate, and has properties similar to those of a pseudo-porous film. In particular, to modify the pre-treatment film embedded in a groove with a high aspect ratio, it is preferable to gradually increase the pressure inside the chamber when introducing hydrogen peroxide gas into the chamber.
[0038] When the groove width (e.g., about 5 to 50 nm) is small relative to the molecular mean free path (e.g., about 1 μm at 10 kPaA), the gas diffuses due to collisions with molecules forming the film to be processed and with the side surfaces of the grooves in the semiconductor substrate. Therefore, by combining a process of lowering the pressure before introducing hydrogen peroxide gas into the chamber and a process of gradually increasing the pressure inside the chamber, it is possible to utilize the pressure gradient to introduce hydrogen peroxide gas deep into high aspect ratio grooves, thereby facilitating film modification.
[0039] According to the modification method of this embodiment, highly concentrated hydrogen peroxide is introduced into a chamber, and by utilizing the strong oxidizing power and reactivity of hydrogen peroxide, it is possible to modify the unprocessed film at 300°C or less. Furthermore, the surface of the semiconductor substrate is not oxidized at 300°C or less, and only the unprocessed film can be selectively modified. The modification method of this embodiment is an extremely useful technique for filling fine grooves with high-quality insulating material (particularly a technique for modifying films such as polysilazane films) in the manufacturing process of advanced semiconductors, which are becoming increasingly dense and highly integrated.
[0040] For example, the pre-treatment film can be modified into a silicon dioxide film with a refractive index of 1.45 to 1.47 by the modification step. Examples of pre-treatment films that serve as precursors of such silicon dioxide films include films containing at least one of polysilazane, amorphous silicon dioxide, and silicon dioxide. [Example]
[0041] The present invention will be specifically described below with reference to examples.
[0042] Example 1 (treatment pressure 100 kPaA, hydrogen peroxide concentration 5 vol%) A polysilazane solution was dropped onto a silicon substrate with fine grooves (5 nm wide, aspect ratio 100) and spin-coated at 500 rpm. The substrate was then pre-baked at 70°C for 3 minutes to produce a 100 nm thick polysilazane film. As shown in Figure 2, the polysilazane film was deposited both inside and outside the grooves (on the surface of the substrate). In addition to the polysilazane film, amorphous silicon and silicon dioxide films were also deposited by chemical vapor deposition.
[0043] The polysilazane film, amorphous silicon film, silicon dioxide film, and silicon substrate with an area for surface oxidation evaluation were placed in a chamber, and nitrogen was flowed and the temperature was raised. The treatment conditions were a temperature of 50°C, a pressure of 100 kPaA, and a treatment time of 30 minutes. A quartz tube (tubular furnace) with an inner diameter of 50 mm and a length of 1000 mm was used as the chamber.
[0044] Hydrogen peroxide gas was supplied using a RASIRC Peroxidizer, which was operated under conditions that allowed for a hydrogen peroxide gas concentration of 5 vol% to be supplied. The gas consisted of 5 vol% hydrogen peroxide gas, 21 vol% water vapor, and the remainder nitrogen carrier gas (flow rate 5 SLM). The concentration of hydrogen peroxide gas was measured using a Teledyne hydrogen peroxide concentration meter, and it was confirmed that 5 vol% hydrogen peroxide gas was being supplied.
[0045] In the table, the pre-introduction pressure and post-introduction pressure refer to the pressures before and after hydrogen peroxide gas is introduced into the chamber, respectively. The hydrogen peroxide gas molecular flux Γ is expressed in exponential notation with an E between the mantissa and exponent. The flow rate Q1 indicates the value (SLM) at 25°C and 100 kPa, and the flow rate Q2 is a value (L / min) that takes into account the temperature and pressure under the processing conditions. The flow rate within the tube is a value that takes into account the cross-sectional area of the tubular furnace, and the residence time within the tube is a value that takes into account the length of the tubular furnace.
[0046] Before and after the hydrogen peroxide gas treatment, the samples outside the grooves of the substrate were evaluated using a spectroscopic ellipsometer and infrared absorption. The nitrogen content of the samples inside the grooves of the substrate was also evaluated using X-ray photoelectron spectroscopy (XPS).
[0047] Before treatment, the refractive index (wavelength 632.8 nm) measured by a spectroscopic ellipsometer was 1.75 to 1.80 for the polysilazane film, 1.67 to 1.70 for the amorphous silicon film, and 1.54 to 1.56 for the silicon dioxide film. After treatment, the refractive index was 1.45 to 1.47 for all films. Since the refractive index of ideal silicon dioxide (wavelength 632.8 nm) is 1.45, it was confirmed that each sample had been modified to silicon dioxide by hydrogen peroxide gas treatment.
[0048] The infrared absorption wavelength of the film was evaluated by measuring the Si-N (920 cm -1 ), Si-H (2120cm -1 ), Si-O (1070cm -1 ) was evaluated. Before and after the hydrogen peroxide gas treatment, the Si-N and Si-H components decreased, while the Si-O component increased. This confirmed that the hydrogen peroxide gas treatment removed nitrogen and hydrogen from the polysilazane film, introduced oxygen, and modified the sample film to silicon dioxide (see Figure 3). Furthermore, when the nitrogen content in the grooves was evaluated using XPS, it was confirmed that the nitrogen content was the same at the top of the groove (around aspect ratio 0) and the deepest part (around aspect ratio 100). This confirmed that hydrogen peroxide had reached the deepest part of the grooves in both samples, modifying the film. Furthermore, under these processing conditions, the thickness of the oxide film on the silicon substrate did not change (the difference between before and after processing was 0.0 nm), confirming that oxidation of the silicon substrate was suppressed.
[0049] Examples 2 to 6 (treatment pressure 100 kPaA) In Examples 2 to 6, the processing conditions for each sample film (polysilazane film, amorphous silicon film, silicon dioxide film, and silicon substrate having a region for evaluating surface oxidation) were adjusted as follows: temperature: 100°C (Example 2), 150°C (Example 3), 200°C (Example 4), 250°C (Example 5), or 300°C (Example 6), pressure: 100 kPaA, and processing time: so that the degree of modification was equivalent to the result of Example 1. All other conditions were the same as in Example 1. The results of Examples 2 to 6, similar to those obtained in Example 1, confirmed that the modification to silicon dioxide had progressed based on the spectroscopic ellipsometer and infrared absorption wavelength evaluation. Similarly to the results obtained in Example 1, the nitrogen content in the grooves measured by XPS confirmed that hydrogen peroxide had reached the deepest part of the grooves and modified the film. Furthermore, under these processing conditions, the thickness of the oxide film on the silicon substrate did not change, confirming that oxidation of the silicon substrate was suppressed. (See Tables 1 to 3 for the results.)
[0050] Examples 7 to 10 (treatment pressure 10 kPaA) In Examples 7 to 10, the treatment conditions for the silicon substrate having the polysilazane film and the area for evaluating surface oxidation were adjusted to a temperature of 50°C (Example 7), 100°C (Example 8), 200°C (Example 9), or 300°C (Example 10), a pressure of 10 kPaA, and a treatment time so that the degree of modification was equivalent to the result of Example 1. Other conditions were the same as in Example 1. The results of Examples 7 to 10, similar to those obtained in Example 1, confirmed that the modification to silicon dioxide had progressed based on the spectroscopic ellipsometer and infrared absorption wavelength evaluation. Similarly to the results obtained in Example 1, the nitrogen content in the grooves measured by XPS confirmed that hydrogen peroxide had reached the deepest part of the grooves and modified the film. Furthermore, under these processing conditions, the thickness of the oxide film on the silicon substrate did not change, confirming that oxidation of the silicon substrate was suppressed. (See Table 4 for the results.)
[0051] Examples 11 to 14 (treatment pressure 1 kPaA) In Examples 11 to 14, the treatment conditions for the silicon substrate having the polysilazane film and the area for evaluating surface oxidation were adjusted to a temperature of 50°C (Example 11), 100°C (Example 12), 200°C (Example 13), or 300°C (Example 14), a pressure of 1 kPaA, and a treatment time so that the degree of modification was equivalent to the result of Example 1. Other conditions were the same as in Example 1. The results of Examples 11 to 14, similar to those obtained in Example 1, confirmed that the modification to silicon dioxide had progressed based on the spectroscopic ellipsometer and infrared absorption wavelength evaluation. Similarly to the results obtained in Example 1, the nitrogen content in the grooves measured by XPS confirmed that hydrogen peroxide had reached the deepest part of the grooves and modified the film. Furthermore, under these processing conditions, the thickness of the oxide film on the silicon substrate did not change, confirming that oxidation of the silicon substrate was suppressed. (See Tables 4 and 5 for the results.)
[0052] Examples 15 to 18 (Hydrogen peroxide concentration 2.5%) In Example 15, the processing conditions for the silicon substrate having a polysilazane film and a surface oxidation evaluation region were a temperature of 50°C, a pressure of 100 kPaA, and a processing time adjusted so that the degree of modification was equivalent to the results of Example 1. Operation was performed under conditions that allowed the supply of hydrogen peroxide gas at a concentration of 2.5 vol%. The gas consisted of 2.5 vol% hydrogen peroxide gas, 10.5 vol% water vapor, and the remainder nitrogen carrier gas (flow rate 5 SLM). The concentration of hydrogen peroxide gas was measured using a Teledyne hydrogen peroxide concentration meter, and it was confirmed that 2.5 vol% hydrogen peroxide gas was being supplied. In Examples 16 to 18, the treatment conditions for the polysilazane film and the silicon group for evaluating surface oxidation were adjusted to a temperature of 100°C (Example 16), 200°C (Example 17), or 300°C (Example 18), a pressure of 100 kPaA, and a treatment time so that the degree of modification was equivalent to the result of Example 1. Other conditions were the same as in Example 15. The results of Examples 15 to 18, similar to those obtained in Example 1, confirmed that the modification to silicon dioxide had progressed based on the spectroscopic ellipsometer and infrared absorption wavelength evaluation. Similarly to the results obtained in Example 1, the nitrogen content in the grooves measured by XPS confirmed that hydrogen peroxide had reached the deepest part of the grooves and modified the film. Furthermore, under these processing conditions, the thickness of the oxide film on the silicon substrate did not change, confirming that oxidation of the silicon substrate was suppressed. (See Table 5 for the results.)
[0053] Examples 19 to 22 (Hydrogen peroxide concentration 1.0%) In Example 19, the processing conditions for the silicon substrate having a polysilazane film and a surface oxidation evaluation region were a temperature of 50°C, a pressure of 100 kPaA, and a processing time adjusted so that the degree of modification was equivalent to the results of Example 1. Operation was performed under conditions that allowed the supply of hydrogen peroxide gas at a concentration of 2.5 vol%. The gas consisted of 1.0 vol% hydrogen peroxide gas, 4.2 vol% water vapor, and the remainder nitrogen carrier gas (flow rate 5 SLM). The concentration of hydrogen peroxide gas was measured using a Teledyne hydrogen peroxide concentration meter, and it was confirmed that 1.0 vol% hydrogen peroxide gas was being supplied. In Examples 20 to 22, the treatment conditions for the polysilazane film and the silicon group for surface oxidation evaluation were adjusted to a temperature of 100°C (Example 20), 200°C (Example 21), or 300°C (Example 22), a pressure of 100 kPaA, and a treatment time so that the degree of modification was equivalent to the result of Example 1. Other conditions were the same as in Example 19. The results of Examples 19 to 22, similar to those obtained in Example 1, confirmed that the modification to silicon dioxide had progressed based on the spectroscopic ellipsometer and infrared absorption wavelength evaluation. Similarly to the results obtained in Example 1, the nitrogen content in the grooves measured by XPS confirmed that hydrogen peroxide had reached the deepest part of the grooves and modified the film. Furthermore, under these processing conditions, the thickness of the oxide film on the silicon substrate did not change, confirming that oxidation of the silicon substrate was suppressed. (See Table 6 for the results.)
[0054] Examples 23 and 24 (Effect of evacuation before treatment) In Examples 23 and 24, a silicon substrate having a polysilazane film and a surface oxidation evaluation region was placed in a chamber, nitrogen was flowed in to raise the temperature, and then the pressure was evacuated to 0.01 kPaA (Example 23) or 0.1 kPaA (Example 24) before hydrogen peroxide gas was introduced into the chamber. Hydrogen peroxide gas was then introduced into the chamber while gradually increasing the pressure within one minute to treat the polysilazane film, with the treatment conditions being a temperature of 300°C, a pressure of 100 kPaA, and a treatment time adjusted so that the degree of modification was equivalent to the result of Example 1. Other conditions were the same as in Example 1. The results of Examples 23 and 24, similar to those obtained in Example 1, confirmed that the modification to silicon dioxide had progressed based on spectroscopic ellipsometry and infrared absorption wavelength evaluation. Similarly to the results obtained in Example 1, the nitrogen content in the grooves measured by XPS confirmed that hydrogen peroxide had reached the deepest part of the grooves and modified the film, confirming that hydrogen peroxide had reached the deepest part of the grooves and modified the film. In particular, by evacuating the chamber before introducing hydrogen peroxide gas, as in Examples 23 and 24, the pressure gradient effect contributed to the diffusion of the gas, promoting the diffusion of hydrogen peroxide gas within the film and enabling modification to the deepest part of the grooves in a shorter time. Furthermore, under these processing conditions, the thickness of the oxide film on the silicon substrate did not change, confirming that oxidation of the silicon substrate was suppressed. (See Table 6 for results.)
[0055] Comparative Examples 1 and 2 In Comparative Examples 1 and 2, a polysilazane film and a silicon substrate having a surface oxidation evaluation region were placed in a chamber, and nitrogen was flowed and the temperature was raised. The polysilazane film treatment conditions were a temperature of 450°C, a pressure of 100 kPaA (Comparative Example 1) or 1 kPaA (Comparative Example 2), and a treatment time of 2.5 minutes. The other conditions were the same as in Example 1. The results of the polysilazane film treatment in Comparative Examples 1 and 2 confirmed that the film had been modified to silicon dioxide, based on evaluation using a spectroscopic ellipsometer and infrared absorption wavelength. The nitrogen content in the grooves measured by XPS also confirmed that hydrogen peroxide had reached the deepest part of the grooves, and the film had been modified, similar to the results obtained in Example 1. However, under these treatment conditions, the thickness of the oxide film on the silicon substrate increased by 1.3 nm (Comparative Example 1) and 0.4 nm (Comparative Example 2), respectively, indicating that the silicon substrate had been oxidized. (See Table 7 for the results.)
[0056] Comparative Examples 3 and 4 In Comparative Examples 3 and 4, a polysilazane film and a silicon substrate having a region for evaluating surface oxidation were placed in a chamber, and nitrogen was flowed and the temperature was raised. The polysilazane film treatment conditions were a temperature of 25°C, a pressure of 100 kPaA (Comparative Example 3) or 1 kPaA (Comparative Example 4), and a treatment time of 60 minutes. The other conditions were the same as in Example 1. The results of the polysilazane film treatment in Comparative Examples 3 and 4 showed that the refractive index before and after treatment was 1.54 to 1.56 using a spectroscopic ellipsometer, confirming that the film had been slightly modified to silicon dioxide. Evaluation of infrared absorption wavelengths also showed a slight decrease in the absorption wavelengths of Si-N and Si-H, and a slight increase in the absorption wavelength of Si-O, confirming that the film had been modified to silicon dioxide. However, despite the long treatment time, the modification did not progress sufficiently. Evaluation of the nitrogen content in the grooves using XPS confirmed that the highest point (near an aspect ratio of 0) and the deepest part (near an aspect ratio of 100) of the groove contained a large amount of nitrogen, confirming that the film had not been modified to the deepest part of the groove. Furthermore, under these treatment conditions, the thickness of the oxide film on the silicon substrate did not change (the difference between before and after treatment was 0.0 nm), and no increase in infrared absorption of Si-O was observed, confirming that oxidation of the silicon substrate was suppressed. (See Table 7 for results.)
[0057] Comparative Examples 5 and 6 In Comparative Examples 5 and 6, a silicon substrate having a polysilazane film and a surface oxidation evaluation region was placed in a chamber, and nitrogen was flowed and the temperature was raised. The polysilazane film treatment conditions were a temperature of 300°C (Comparative Example 5) or 50°C (Comparative Example 6), a pressure of 100 kPaA, and a treatment time of 60 minutes. Hydrogen peroxide gas was generated by heating a 30% aqueous hydrogen peroxide solution to 120°C using a rotary evaporator. The concentration of the hydrogen peroxide gas was measured using a Teledyne hydrogen peroxide concentration meter, and it was confirmed that 0.02 vol% hydrogen peroxide gas was supplied. The other conditions were the same as in Example 1. The results of the polysilazane film treatment in Comparative Examples 5 and 6 showed that the refractive index before and after treatment was 1.54 to 1.56 using a spectroscopic ellipsometer, confirming that the film had been slightly modified to silicon dioxide. Evaluation of infrared absorption wavelengths also showed a slight decrease in the absorption wavelengths of Si-N and Si-H, and a slight increase in the absorption wavelength of Si-O, confirming that the film had been modified to silicon dioxide. However, despite the long treatment time, the modification did not progress sufficiently. Evaluation of the nitrogen content in the grooves using XPS confirmed that the highest point (near an aspect ratio of 0) and the deepest part (near an aspect ratio of 100) of the groove contained a large amount of nitrogen, confirming that the film had not been modified to the deepest part of the groove. Furthermore, under these treatment conditions, the thickness of the oxide film on the silicon substrate did not change (the difference between before and after treatment was 0.0 nm), and no increase in infrared absorption of Si-O was observed, confirming that oxidation of the silicon substrate was suppressed. (See Table 8 for results.)
[0058] Comparative Examples 7 and 8 In Comparative Examples 7 and 8, a polysilazane film and a silicon substrate having a surface oxidation evaluation region were placed in a chamber, and nitrogen was flowed and the temperature was raised. The polysilazane film treatment conditions were a temperature of 50°C (Comparative Example 7) or 300°C (Comparative Example 8), a pressure of 0.1 kPaA, and a treatment time of 60 minutes. The other conditions were the same as in Example 1. The results of the polysilazane film treatment in Comparative Examples 7 and 8 showed that the refractive index before and after treatment was 1.54 to 1.56 using a spectroscopic ellipsometer, confirming that the film had been slightly modified to silicon dioxide. Evaluation of infrared absorption wavelengths also showed a slight decrease in the absorption wavelengths of Si-N and Si-H, and a slight increase in the absorption wavelength of Si-O, confirming that the film had been modified to silicon dioxide. However, despite the long treatment time, the modification did not progress sufficiently. Evaluation of the nitrogen content in the grooves using XPS confirmed that the highest point (near an aspect ratio of 0) and the deepest part (near an aspect ratio of 100) of the groove contained a large amount of nitrogen, confirming that the film had not been modified to the deepest part of the groove. Furthermore, under these treatment conditions, the thickness of the oxide film on the silicon substrate did not change (the difference between before and after treatment was 0.0 nm), and no increase in infrared absorption of Si-O was observed, confirming that oxidation of the silicon substrate was suppressed. (See Table 8 for results.)
[0059] [Table 1]
[0060] [Table 2]
[0061] [Table 3]
[0062] [Table 4]
[0063] [Table 5]
[0064] [Table 6]
[0065] [Table 7]
[0066] [Table 8]
[0067] In this technology, we found that by introducing high-concentration hydrogen peroxide into a chamber and utilizing the strong oxidizing power and reactivity of hydrogen peroxide, we could modify polysilazane films at temperatures below 300°C. Furthermore, the surface of the silicon substrate is not oxidized at temperatures below 300°C, making it possible to selectively modify only the polysilazane film. This technology is extremely useful as a technology for filling fine grooves with high-quality insulating material (a technology for modifying polysilazane films) in the manufacturing process of cutting-edge semiconductors, which are becoming increasingly dense and highly integrated. Furthermore, in the above-mentioned Examples 1 to 6, we were able to confirm that amorphous silicon dioxide and silicon dioxide could also be modified. [Explanation of symbols]
[0068] 10...semiconductor substrate, 11...coated film, 12...film before treatment, 12a...portion deposited on the surface, 12b...portion deposited in the groove, 13...modified film, 14...surface, 15...groove, t...thickness, d...groove depth, w...groove width.
Claims
1. A modification method including a modification step of modifying a semiconductor substrate having a pre-processed film deposited thereon by exposing the semiconductor substrate, which is held in a chamber heated to a temperature of 50°C to 300°C, to a gas atmosphere containing hydrogen peroxide in the chamber, The concentration of hydrogen peroxide gas contained in the gas atmosphere is 1 to 5 vol% (volume percentage), The gas molecular flux Γ of hydrogen peroxide in the chamber is 9.4×10 １９ ~1.3 x 10 ２２ (pcs / (cm) ２ sec)) is a modification method.
2. 2. The modifying method according to claim 1, wherein the untreated film deposited on the semiconductor substrate contains at least one of polysilazane, amorphous silicon dioxide, and silicon dioxide.
3. 3. The method according to claim 1, further comprising the step of evacuating the pressure in the chamber to 0.01 kPaA (absolute pressure) to 0.1 kPaA before introducing hydrogen peroxide gas into the chamber in the modification step.
4. The modification method according to claim 1 or 2, characterized in that the semiconductor substrate has a groove having a groove width of 5 nm or more and an aspect ratio of 100 or less, and the pre-processed film includes a portion deposited in the groove.
5. 3. The modifying method according to claim 1, wherein the untreated film is modified into a silicon dioxide film having a refractive index of 1.45 to 1.47 by the modifying step.
Citation Information
Patent Citations
Bucket burying prevention type grit scraping and lifting machine
JP1982010308A
Photosensitive body
JP1988081486A