TW518689B - Control method for plasma etching process - Google Patents

Abstract

A control method for plasma etching process is provided, in which the control method for plasma etching process according to the present invention can adjust the etching process based on the relative intensities of the etching product and the reactant on the mass spectra or the optical spectra. The inventive control method for plasma etching process can perform in-situ and real-time control of the plasma etching process to ensure obtaining the expected etching result at the end of etching, even though the etching objects have different pattern densities.

Description

518689 A7

V. Description of the invention () Field of invention: Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs. The invention relates to a method for controlling a plasma etching process, and in particular, it relates to a variety of electric objects with different pattern densities. Control method of the engraving process. Background of the invention: In the plasma etching reactor, in addition to the design of the electrode plate, the input and output of the pendulum reaction of the wafer, and the placement of radio frequency (RF) power, the choice of the end detector also affects the etching. Process control has a decisive effect. The so-called end point detector is a detection device used to help the etching technician determine whether the etching of the thin film has reached the end point, so as to avoid the problem of under-etching or over-etching. Because in the mass-produced semiconductor manufacturing process, in order to ensure that the etched film is completely removed during the etching step, after the initial etching is completed, an over-etch of varying degrees is added to compensate for the problem. The thickness of the film is uneven, or the etching gap caused by other factors. The judgment of the degree of the end of the etching and the degree of over-etching is based on the use of the end detector. At present, the equipment is equipped with various end point detectors, mainly using optical emissivity (laser interferonietry) and laser interference measurement (laser interferonietry) to perform the end point detection of the paddle etching process. The optical radiation method is to use the 2 paper sizes issued by the plasma to comply with the Chinese National Standard (CNS) A4 specification (210 X 297 mm). 1 -------: --- W # (please read first Note on the back, please fill out this page) ---- Order ----- 华 ° i〇689

Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs. 5. Description of the Invention () Light's monitoring of the specific gas emission spectrum to determine the end point of the etching reaction. The laser interference measurement rule is a measure of optical interference at a point ' W laser beam on an etched area on a wafer. When the intensity of the laser light no longer has the interference phenomenon of the incident light and the reflected light caused by the film thickness, the end point of surface etching has reached. The above-mentioned optical emission method is based on a spectrometer attached to the etching machine. The light emission spectrum of the specific gas is monitored by the light emitted from the polymerization to determine whether the end of the electrical assembly process has been reached. Please refer to the plasma in Figure 1 for the spectrum of products and reactants produced by the spectrometer in the remaining process. In FIG. 1, the etched film is, for example, silicon, the reaction gas is, for example, chlorine gas, and the product is, for example, silicon chloride. In addition, the horizontal axis of the figure 丨 is the wavelength, and the vertical axis is the relative intensity. The greater the relative strength of a substance, the greater the amount of this substance in the etching reaction chamber. It is conventional to use optical radiation to determine the endpoint of the etch by monitoring the relative intensity of the reaction gas or product in Figure 1. At the beginning of the etching process, the reaction gas is passed into the reaction chamber, so the relative strength of the reaction gas or the product is a specific value. When the intensity of the spectral line of a product is greatly increased or decreased, it is known that the etched film has been etched or etched to the underlying film at this time, and this is the end point of the etching. The above-mentioned conventional method of determining the end point of etching by optical radiation method is only applicable to the end point of the film to be etched. The end point of the etched film is the obvious interface between the two materials or the end point of the material of the film. If it is such as shallow trench isolation (ShaU〇W trench, this paper rule is standard (CNS) A4 specification (210-·, --- '" ^ 1 ^ 装 -------- Order-- ------- (Please read the notes on the back before filling out this page) 518689 Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 B7 V. Invention Description () isolation; STI) technology or dual mosaic (dliai In damascene) technology, the bottom of the trench caused by the last name is not the obvious interface between the two materials or the end point of the material of the film, then the conventional method of determining the #etch end point by optical radiation method will be reported. Failure. Please refer to the structure cross-section of the conventional shallow trench isolation technology in Figure 2A. The substrate 1 in Figure 2A has a trench formed using shallow trench isolation technology, and the bottom of the trench 12 is not located The interface between the substrate 10 and another material (not shown). Please also refer to the cross-sectional view of the structure of the conventional double inlay technology in FIG. 2B. The dielectric layer 1 on the substrate 1 3 in FIG. 2B 4 has trenches 15 and interlayer holes 16 formed by the dual damascene technology, and the bottom of the trench 17 is not located between the dielectric layer 14 and the substrate 1 3 Junction. In order to solve the problem of determining the etching end point encountered in the shallow trench isolation technology or the dual damascene technology, the conventional etching engineer mostly determines the etching time required to reach the etching end point by repeated experiments. However, In fact, this is not an effective method. For a wafer foundry, different wafers that an etching engineer needs to face may have different patterns. This difference means that different patterns on the circle cause different pattern densities. Pattern density It refers to the ratio of the area that does not need to be etched to the total area on a thin film. When the pattern density is larger, it means that the area that must be etched on the diaphragm is smaller, and the etching time required to etch to a certain depth is less. Conversely, the smaller the pattern density, the larger the area that must be etched on the surface film, and the more etch time required to etch to a certain depth at this time. Therefore, the actual practice of the conventional etching engineer is to use the new pattern Before the film is etched, first set a specific time to enter the paper scale. Wealth and wealth (CNS) A4 (2iq χ 297 public love) ---------- ( (Please read the notes on the back before filling this page) -H ϋ i_i H 1 I ϋ · n ϋ 华 518689

V. Description of the invention () Line-the first etching. If the etching depth caused by this first etching is too large, a shorter etching time is set in the next etching. Conversely, if the depth of the hafnium caused by the first remaining time is not ^, set a longer etching time at the next time. Purpose and summary of the invention: In the above background of the invention, the disadvantages of the control method of plasma etching process are known. The purpose of the present invention is to provide a control method of plasma plasma etching process, which can be used in the field (in- situ) and real time control the plasma etching system to ensure that the desired etching result can be achieved at the end of the etching, even if the etched objects have different patterns of dense production. (Please read the precautions on the back before filling out this page) Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs According to the above purpose of the present invention, the present invention provides a method for controlling plasma money engraving process. The method for controlling the plasma etching process of the present invention includes the following steps: when the plasma control system is activated for a specific time, using a spectrometer or a mass spectrometer to collect the spectrum of the products and reactants or spectral line data of the mass spectrum; then, calculating the spectral line data The ratio of the relative strength of the product to the reactant; then, the ratio is immediately transmitted to the plasma control system; and the plasma control system based on the empirical value database of the plasma control system for the relative strength of the product and the relative strength of the reactant The plasma parameter corresponding to the ratio is automatically adjusted, and the etching can be performed immediately according to the adjusted electrical parameters to achieve the desired etching result. This paper size applies to Chinese National Standard (CNS) A4 (210 X 297 mm). Stupid 丨 518689

V. Description of the invention () Brief description of the drawings: The preferred embodiment of the present invention will be described in more detail in the following explanatory text with the following patterns, where: Figure 1 shows the plasma surname engraving process. The spectrum of the products and reactants produced by the spectrometer; Figure 2A is a structural cross-sectional view of the conventional shallow trench isolation technology; Figure 2B is a structural cross-sectional view of the conventional dual mosaic technology; Figure 3 is a comparison of the present invention The relationship between the plasma parameter and the ratio A / B of the relative intensity A of the product obtained by the spectrometer and the relative intensity B of the reactant in the preferred embodiment; Figure 4 is the product produced by the mass spectrometer in the plasma etching process And the mass spectrum of the reactant; Figure 5 is the relationship between the plasma parameter and the ratio A / B of the relative intensity a of the product obtained by the mass spectrometer and the relative intensity B of the reactant in another preferred embodiment of the present invention. And FIG. 6 is a flowchart of a method for controlling a plasma etching process according to a preferred embodiment of the present invention. Drawing number comparison description: This paper size applies to Chinese National Standard (CNS) A4 € each (210 X 297 male f) (Please read the precautions on the back before filling this page)

-H 1 ϋ > ϋ i —i 一 OJ · 1 «ϋ I Μτ, printed by the Consumer Cooperative of Intellectual Property Bureau of the Ministry of Economic Affairs 518689 Printed by A7 of the Intellectual Property Bureau of the Ministry of Economic Affairs Η printed by Consumer Cooperatives V. Description of invention () 10 substrates 11 trench 12 trench bottom 13 substrate 14 dielectric layer 15 trench 16 via hole 17 trench bottom

1 1 0 When the electropolymerization control system is activated for a specific time, use the spectrometer or mass spectrometer E to collect the spectrum of the product and the reactant or the spectrum data of the mass spectrum. 1 20 Calculate the relative intensity a of the product in the spectrum data and the relative intensity of the reactant. The ratio of B a / B 130 transmits the ratio A / B to the plasma control system. 14 Electric music: The control system automatically adjusts the plasma parameters corresponding to the ratio A / B in the experience database of the plasma control system. The etching is performed according to the adjusted plasma parameters to achieve the desired etching result. The ratio of the relative strength of the A / B product a to the relative strength of the reactant b is described in detail in the invention. As described in the background of the above invention, for example, in the shallow trench isolation technology or It is the appearance of the trench to be etched in the dual damascene technology because there is no obvious interface between the two materials or the end point of the thin film. Therefore, it is known to determine the end point of the etching by the intensity change of the product (or reactant) produced by the spectrometer. This will not work. However, a preferred embodiment of the present invention is the spectrometer of the aforementioned figure 丨 -------------------- order --------- 3— , (Please read the precautions on the back before filling this page) 51S689

On the other hand, the reverse application of Sicheng can be used to determine the results such as shallow trench isolation or double-inlaid towels. Even if it is engraved with the surname ^ I (the uranium on the film has a different pattern from the circle / (the ratio of the area on the film that is not etched and the ratio of -Xigu and soil k P i), it can also be produced by the present On the day, the method can easily determine the results of different pattern dense engraving. For the fragrance corresponding to the line / clothing degree, please refer to Figure i again. The base of the present invention RB J »-T- ΛΑΓ …: J is a spectrometer at a certain moment in the process of engraving the surname ... π. As can be seen from the i-th figure, the material being etched is silicon, and the reactant that passes into the plasma is gas and gas Coordinated by Feng Liaohua. In addition, the horizontal coordinate of layer J is the wavelength, and the vertical coordinate is the relative intensity. In the case of passing through the same etched isthmus, the larger the picture size, the smaller the match must be, so therefore Fewer products are produced, and more reactants remain, that is, the relative strength of the product is smaller, and the relative strength of the reactants is greater. Conversely, for the same pattern time, for a smaller pattern density And e 'must have a larger area of 14 ticks, so more products are produced, and the remaining Reactants, i.e., the relative strength of the product is large, and the reaction product of a relatively small intensity. (Note that the matters Read then fill the back page)

-ϋ ϋ I nn I ϋ · n ϋ I Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs According to the above-mentioned basic concept of the present invention, if the relative strength of the product to be etched is A, and the relative strength of the remaining reactants is Is B, then the ratio A / B obtained in the plasma etching process can be used to determine the 8 paper sizes corresponding to a pattern density. The Chinese national standard (CNS) A4 specification (210 X 297 mm) is applicable. Printed by the Consumer Cooperatives of the Bureau 518689 A7 ____ B7 5. The plasma parameters of the invention description (), and further adjust the plasma control system based on the plasma parameters, so that the adjusted plasma parameters can be reached to the expected etching end point. . Please refer to FIG. 3, which is a graph of the relationship between the number of plasmitis and the ratio A / B obtained by a spectrometer in a preferred embodiment of the present invention. In another preferred embodiment of the present invention, a mass spectrometer can be used instead of a spectrometer. Please refer to Figure 4. Figure 4 shows the mass spectrum produced by an Esther spectrometer at a moment in the etching process. It can be seen from Fig. 4 that the material to be etched is Shi Xi, and the reactant that passes into the plasma reaction chamber is chlorine gas, and the product is vaporized. The abscissa of Fig. 4 is the molecular weight and the ordinate is the relative strength. Figure $ shows the relationship between the plasma parameters and the ratio A / B obtained by the mass spectrometer in another preferred embodiment of the present invention. Before carrying out the method of the present invention, it is necessary to obtain the relationship diagram of the ratio A / b and the pattern density, wherein the relationship diagram can be further converted into the relationship diagram of the ratio a / b and the plasma parameters. Then, in the method for controlling the plasma plasma etching process of the present invention, the relationship diagram of the above-mentioned ratio A / B and plasma parameters can be repeatedly used. In addition, the control method of the plasma etching process of the present invention is used to etch the first wafer in a batch of wafers having the same pattern density. This method includes at least the following steps. Please refer to FIG. 6 for the control method of the plasma etching process of the present invention. First of all, as in step 1, the spectral data of the product and the reactant are collected at the start of the plasma control system for a specific time. The reactant may be, for example, a gas used for money engraving or a treasure or reference engraved by engraving. Electrical quality, metal, etc. 9 This paper size is applicable to China National Standard (CNS) A4 specification (210 X 297 male f) (Please read the precautions on the back before filling this page) -IIIII ϋ I 一 ： 口 、 II n I ϋ 518689 The A7 I printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs, the invention description (and this spectrum data can be, for example, the spectrum obtained by the Nine Photometer & ^ ^ Nine μ instrument or the mass spectrum obtained by a mass spectrometer. When the so-called specific time and order are not at this specific time, although the result of the plasma etching is not reached, the ratio A / B of the plasma reaction to the anti-analysis 4 has been approximated by the ratio A / B of the etching result. The ratio of this specific time Α / Β can be used as Α / Β 'for the rest of the results to set the plasma parameters required to carry out the cardioversion to the etching results. Usually it takes only a few seconds to reach this specific Time. Then 'calculate this spectral line as step 120 The ratio of the relative strength of the product and the reactant A / B. Then, the ratio M is transmitted to the plasma control system in step 13. Then, in step 14 the plasma control system is based on the empirical value database of the plasma control system. The electric parameters corresponding to the ratio A / B are automatically adjusted, that is, after the trimming < the plasma parameters are achieved in the remaining time to achieve the desired axial engraving results. The aforementioned plasma parameters may be, for example, time, temperature, pressure, power, and Gas flow rate, etc. In summary, the advantages of the plasma etching process control method of the present invention are that the plasma etching process can be controlled in real-time and real-time to ensure that the desired value can be achieved at the end of # 刻The end point of the etch, even if the engraved objects have different pattern densities. As understood by those skilled in the art, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of patent application of the present invention; All other equivalent changes done without departing from the spirit disclosed by the present invention 10 This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) .-------- * 4-- - ------- Order --------- (Please read the notes on the back before filling this page) 518689 A7 _B7_ V. Description of the invention () Changes or modifications should be included in the following Within the scope of applying for a patent (Please read the notes on the back before filling this page) tr --------- Printed by the Consumers' Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs This paper is printed in accordance with China National Standard (CNS) A4 (210 X 297 mm)

Claims (1)

518689 Intellectual Property Bureau, Ministry of Economic Affairs, Employee Consumption Cooperatives, Printed Clothes A8, B8, C8, D8 6. Application for Patent Scope 1. A plasma money engraving process control method, applicable to multiple wafers and plasmas with multiple patterns. The control system is activated for a specific time 'and a reactant and a product are formed through the control of the plasma control system in a plasma etching process of each of the wafers, wherein the method of controlling the plasma etching process includes at least : Collecting spectral data of the product and the reactant; calculating a ratio of a relative intensity of the product to a relative intensity of the reactant in the spectral data; transmitting the ratio to the plasma control system; and the The plasma control system automatically adjusts a plasma parameter corresponding to the ratio in an empirical value database of the plasma control system, and the plasma parameter can be adjusted to an expected end point of the etching according to the adjusted plasma parameter. 2. The method for controlling the plasma etching process according to item 1 of the scope of the patent application, wherein the spectral line data is generated by a spectrometer. 3. The method for controlling a plasma etching process as described in item 1 of the scope of patent application, wherein the spectrum data is generated by a mass spectrometer. 4. The method for controlling the plasma etching process as described in item 1 of the scope of patent application ', wherein each of these pattern densities represents a ratio of an area that does not need to be engraved to a total area. 12 This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) (Please read the precautions on the back before filling this page) -------- Order -------- The intellectual property bureau of the Ministry of Economic Affairs applies for the scope of patents. 5. If the scope of the patent application is "method," Xi Lei will control the plasma etching process described in the item, where the plasma parameter is time. The electric method described above, wherein the electro-polymerization parameter is temperature. Control 7 • As described in the patent application section “Flute Method”, “the electro-polymerization etching process described in item 1 has been controlled, wherein the plasma parameter is pressure 8. Control method of plasma etching process as described in item 1 of the patent scope of application, where the plasma parameter is power. 9, 9. Control of etching process of electric field as described in item i of patent application scope, i Fang, where the plasma parameter is the gas flow rate. 10. The method for controlling the plasma etching process as described in item i of the patent application scope, wherein the automatic adjustment step can be in-situ. 1 1 · 如Plasma erosion described in the scope of application for item 丨Control method of manufacturing process' wherein the step of automatic adjustment can be real-time (reaMime). --------- M --- installation -------- order --------- (Please read the precautions on the back before filling out this page) Printed by China Consumers' Association 13 This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) 1 2 · As described in item 1 of the scope of patent application Control method of plasma etching process' wherein the reactant is a gas. 518689 A8 B8 C8 D8 6. When the patent application scope map is applied, the control should be performed with a fixed plasma engraving strength. The product has a suitable process for the production of electrical products in Qizhongzhong, which can be used in the process of electricity production. The system must be integrated and manufactured. And the line value control: one of the electric and field spectrum ratio is 7¾ It, the object is close to the journey i, the system should be based on the system and the circle reaction is engraved on the root crystal, and the crystal is strongly etched. The shape of the material and the electricity and the system of the legal system are duplicated for each control line. The spectrum of the control should be 13 degrees and the control should be anti-secret. The process between the cases and --- ----- ^ --- Installation -------- Order --------- (Please read the precautions on the back before filling out this page) The paper printed by the Consumers' Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs applies to this paper China National Standard (CNS) A4 specification (210 X 297 mm)