TW584969B - Method for manufacturing poly-Si of thin-film transistor - Google Patents

Abstract

A method for manufacturing poly-Si of a thin-film transistor comprises providing a substrate; depositing a first amorphous silicon layer on the substrate; using an excimer laser to irradiate the first amorphous silicon layer to form a seed crystal layer; depositing a second amorphous silicon layer on the seed crystal layer; and performing a furnace annealing.

Description

584969 V. Description of the invention (1) (1) [Technical field to which the invention belongs] The present invention relates to a method for manufacturing polycrystalline silicon of a thin film transistor, particularly a low temperature processed (LTP) polycrystalline silicon thin film Method for manufacturing polycrystalline stone of transistor. (2) [Previous technology] Low temperature polycrystalline silicon thin film transistors are generally used in active matrix liquid crystal display (AMLCD) and active organic organic light-emitting display (active matrix organic light-emitting display, AM0LED) and other large area displays. The low temperature polycrystalline silicon thin film transistor has the advantages of a faster electron movement rate and the like, making it one of the new generation mainstream processes. However, to make a high-performance low-temperature polycrystalline silicon thin film transistor, one of the most difficult steps is to convert amorphous silicon (α-S i) into polycrystalline silicon (po! Y silicon, po1y-Si). · In the conventional technology, a solid phase crystallization method (sohd phase crystallization (SPC)) is generally used to convert an amorphous silicon layer on a glass substrate into a polycrystalline silicon layer at a temperature of about 60 (rc). See Figure 丨 A As shown in the figure, an amorphous stone layer 23 is deposited on the surface of a stone substrate 21 with the & buffer oxide layer 22 formed. Then, the amorphous silicon layer 23 is converted into a polycrystalline silicon layer 24 by a solid phase crystallization method. As shown in Figure 1B. However, the solid-phase crystallization method requires a very long process time (about 20-60 hours) to form a larger grain size, so it is not suitable for applications in industrial processes. In addition, the use of Polycrystalline silicon formed by solid-phase crystallization ^ has high-density in-grain defects, even more than one%

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584969 V. Description of the invention (2) Reduced the electrical properties of low temperature polycrystalline silicon thin film transistors. In order to shorten the process time, excimer laser annealing (ELA) is widely used in the industry to convert the amorphous stone layer into a polycrystalline silicon layer, in addition to using the excimer laser annealing method instead of the solid-phase crystallization method. The rest of the process steps are the same as those in FIG. 1A and FIG. 1B. However, due to the extremely high crystallization rate of the excimer laser annealing method, the crystal grains formed are all smaller than 100 nm. In addition, due to the overlapping phenomenon of the laser beam and the stability between pulse and pulse (pulse_pulse_pulse) is higher than i, the inventor of the element characteristics of the recrystallized polycrystalline stone layer was in urgent need of this. "Think of a possible method", several-, ▼, a "thin film transistor research and experiment in the spirit of active invention to solve the above problems until the completion of this benefit of the world: system (three), [invention content In view of the above-mentioned problems, the purpose of the present invention is to produce a process with a short process time and few grain defects. 疋 Polycrystalline silicon with uniform thin film transistors. The feature of the present invention is to use a polycrystalline silicon layer in a transistor. Two steps The annealing method to manufacture the thin film edge is that polycrystalline stone is manufactured and deposited first to form a method for achieving the above purpose, including an amorphous layer, a crystal layer, and a seed layer. According to the present invention, the following steps are used: A thin layer deposited on the excimer crystal layer to provide a substrate laser to irradiate the first and second amorphous film transistors; an amorphous silicon layer silicon layer on the substrate; and

584969 V. Description of the invention (3) Perform furnace tube annealing. As mentioned above, a method for manufacturing a polycrystalline silicon layer of a thin film transistor according to the present invention uses a two-step annealing method to manufacture a polycrystalline silicon layer in a thin film transistor. Compared with the conventional solid-phase crystallization method, the present invention reduces the process time and also reduces the defect density inside the crystal grains. In addition, compared with the conventional excimer laser method, the polycrystalline silicon formed by the present invention is used. Thin-film transistors have consistent device characteristics, and at the same time, polycrystalline silicon layers have larger grain sizes. The detailed comparison is shown in the table below. Solid-phase crystallization method Excimer laser method The device of the present invention has better uniformity and poorer performance. The process time is longer. Shorter and shorter. Grain defects. High density. Low density. Low density. According to the present invention, a thin-film transistor polycrystalline silicon manufacturing method includes the following steps: providing a substrate; depositing a first amorphous silicon layer on the substrate; irradiating the first amorphous silicon layer with an excimer laser to form a Crystal layer; depositing a second amorphous silicon layer on the seed layer; and

584969

Rapid thermal process (RTP) annealing. Components: The above-mentioned manufacturing method of polycrystalline stones for thin film transistors is described below. The choice between A ^, consistency and product productivity is the best choice for industrial applications. (IV) [Embodiment] Hereinafter, a method for manufacturing a polycrystalline silicon of a film transistor will be described with reference to related drawings and symbols. A thin film according to a preferred embodiment of the present invention will be described in which the same elements will be shown in the same figure. FIG. 2 shows a method for manufacturing a thin film transistor according to the first embodiment of the present invention. A substrate (s〇 丨); a first amorphous silicon layer (S0 2) is deposited on the 2 f plate; the amorphous silicon layer is irradiated with an excimer laser to form a crystal layer (s〇3); on the seed layer A second amorphous silicon layer is deposited thereon (s04); and furnace tube annealing is performed (S05). As shown in FIG. 3A, a substrate is provided in step SOI. Here, the substrate 11 may be a silicon substrate or a glass substrate. In this embodiment, a buffer oxide layer (Buffer OXide 丨 ayerH2) is formed on the substrate & 11, which is generated on the surface of the substrate 丨 using a thermal oxidation method. Adhesion of the deposition material to the surface of the substrate 1. Next, as shown in FIG. 3B, in step S 02, a first amorphous silicon layer 13 is deposited on the substrate 11. In this embodiment, si H4 is used. (Silicon methane) is a reactive gas, and the first amorphous silicon layer 13 is deposited by a low pressure chemical vapor deposition (LPCVD) method at a temperature of about 5 50 ° C. A low pressure chemical vapor phase is used. First amorphous

584969 V. Description of the invention (5) The silicon layer 13 has better step coverage ability, and the first amorphous silicon layer 3 has good uniformity and high purity. Here, the thickness of the first amorphous stone layer 13 is about 6 nanometers (nm) to 12 nanometers. In addition, in step S03, the first amorphous stone layer 13 'is irradiated with an excimer laser to form a seed layer (Seed lay §r) 14, as shown in FIG. 3C. In this embodiment, it is at room temperature and close to vacuum (~ 10_3 t〇rr), using erbium fluoride (KrF) excimer laser (laser intensity is 12m J / c m2 ) The first amorphous silicon layer 13 is irradiated to convert it into a crystalline layer 4. Among them, the excimer laser has a wavelength of 248 nm, a pulse sustaining time of 5 ns, and a repetition rate of 1 OHz. In addition, excimer laser can also use argon fluoride

UrF) laser or vaporized xenon (XeC1) laser. Here, the seed layer is a polycrystalline fragment structure. In step 304, a second non-Japanese silicon layer 15 is deposited on the seed layer 14, as shown in FIG. 3D. Among them, The method of redundant recording of the second amorphous silicon layer 15 is the same as that of the first non-Japanese stone 々Q 4 door opening day / continued 1 // 儿 product formula, the second non-Japanese :: /, here No further details. In the first embodiment of this embodiment ::; Shi Xi layer 13 is thinner than the second amorphous Shi Xi layer 15. Steps will be as follows: 3 ΒΕ 'in step so5, the furnace tube annealing is performed. In the example, the polycrystalline silicon layer 16 is charged at a temperature of 550,0 tJ_. The polycrystalline silicon layer 16 is annealed in a furnace tube in an environment where the present embodiment (about 2 to 24 hours) is filled with lice / gas. The crystal is ordered to convert the second amorphous silicon layer 15 to come again, and then formed to form a plurality of unique ::: 2 16 after '16 is a pattern of the polycrystalline silicon layer 16 moving element region. Then, at temperature About

Page 8 584969 Plasma-assisted chemical vapor deposition (piasma) at 30 ° C

Enhanced Chemical Vapor Deposition (PECVD) deposits a TE OS-oxide with a thickness of about 120 nm as the gate insulating layer. Next, a polycrystalline silicon layer with a thickness of about 200 nm is deposited and patterned to form a component gate. Then, a source / drain and a gate region are formed. Next, an activation implantation annealing step was performed in an environment filled with nitrogen at a temperature of 600 ° C for 2 hours. Then again, a TEOS oxide with a thickness of about 500 nm is deposited at a temperature of 300 ° C to form a protective film. Finally, the peripheral electrode bonding terminals are partially exposed to form a low-temperature polycrystalline silicon thin film transistor. In this embodiment, the first amorphous silicon layer is irradiated with an excimer laser to form a seed layer. Since the seed layer has an excellent crystal center, the subsequent crystal grains have a low-density Internal grain defects. Furthermore, since the annealing step of the furnace tube only includes the time required for crystal grain growth, the whole annealing time is greatly shortened. Moreover, since the grain growth mechanism is similar to the solid phase crystallization method, the device characteristics of the polycrystalline silicon thin film transistor produced in this embodiment have better consistency. As shown in FIG. 4, a method for manufacturing polycrystalline silicon of a thin film transistor according to a second embodiment of the present invention includes the following steps: providing a substrate (sn); and depositing a first amorphous stone layer (S1 2) on the substrate Using an excimer laser = the first amorphous silicon layer to form a crystal layer (S1 3); depositing a second amorphous silicon layer (S1 4) on the seed layer; and performing a rapid annealing process ( S15). The thin film transistor made of polycrystalline silicon according to the second embodiment of the present invention is described above, wherein steps S11 to s 1 4 are the same as steps s 〇 1 to s 〇 4 shown in FIG. 2.

Page 9 584969 V. Description of the invention (7) Same as in step S15, the rapid thermal process annealing is performed. This step is also to convert the second amorphous stone layer 15 to a polycrystalline stone layer 1 6 . In the present embodiment, the second amorphous silicon layer 15 is converted into crystals by rapid thermal process annealing (approximately 120 to 30 seconds) in an environment filled with nitrogen at a temperature of 600 to 750 ° C, so that the second amorphous silicon layer 15 is converted into Polycrystalline silicon layer 1 6.

A method for manufacturing polycrystalline silicon of a thin film transistor according to the present invention is to manufacture a polycrystalline silicon layer in a thin film transistor by using a two-step annealing method. Compared with the solid phase crystallization method of the prior art, the present invention reduces the process time, and also reduces the defect density inside the crystal grains. In addition, compared with the conventional excimer laser method, 'the polycrystalline silicon thin film transistor formed by using the present invention has consistent device characteristics' and the polycrystalline silicon layer has a larger grain size. In summary, the polycrystalline silicon manufacturing method of the thin film transistor of the present invention is the best choice for current industrial applications under consideration of element performance, consistency of element characteristics, and product productivity. The above description is exemplary only, and not restrictive. Any equivalent modification or change made without departing from the spirit and scope of the present invention shall be included in the scope of the attached patent application.

Page 10 584969 Brief description of the drawings (five), [Simplified description of the drawings] Figures 1 A and 1 B are schematic diagrams of a method for manufacturing a conventional polycrystalline silicon manufacturing method of a thin film transistor; Figure 2 is a thin film of the first embodiment A block diagram of a polycrystalline silicon manufacturing method for a transistor; FIGS. 3A to 3E are schematic diagrams of a polycrystalline silicon manufacturing method for a thin film transistor in the first embodiment; and FIG. 4 is a polycrystalline silicon manufacturing method for a thin film transistor in the second embodiment. Block diagram.

Description of component symbols: 11 substrate 12 buffer oxide layer 13 first amorphous stone layer 14 crystal layers 15 second amorphous silicon layer 1 6 polycrystalline silicon layer SOI provides a substrate

S 0 2 deposit a first amorphous stone layer 503 on the substrate and irradiate the first amorphous silicon layer with an excimer laser to form a crystal layer 504 deposit a second amorphous silicon layer 505 on the seed layer Furnace tube annealing S1 1 provides a substrate S1 2 to deposit a first amorphous silicon layer on the substrate

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Claims (1)

584969 VI. Application Patent Scope 1. A method for manufacturing polycrystalline silicon of a thin film transistor, comprising: providing a substrate; depositing a first-amorphous silicon layer on the substrate; irradiating the first amorphous silicon with an excimer laser Layer to form a crystal layer; depositing a second amorphous silicon layer on the seed layer; and performing furnace tube annealing. Silicon silicon manufacturing 2. The thin film transistor method described in item 丨 of the patent application scope, further comprising: after the layer is provided, a buffer oxide 3 is formed on the substrate as claimed :: Lifan® 1 The method for manufacturing polycrystalline silicon of the thin film transistor M described in the item, wherein the substrate includes a silicon substrate or a glass substrate. Method, wherein the first non-: polycrystalline stone manufacturing of the thin film transistor described in item 1 of claim 1 is a thinner layer than the second amorphous silicon layer. The thickness of the polycrystalline layer of the first amorphous thin film transistor is about 6 nm to 12 nm. 6. For example, the first method in the scope of patent application, wherein the second amorphous stone is made of polycrystalline stone of thin film transistor, and the thickness of B is about 30 nm to 150 nm, and the polycrystalline powder is made, such as Thin film transistor as described in the first patent application Page 13 584969 VI. Scope of patent application " " '' _ " ------- A method, in which the excimer laser is a fluorinated hafnium laser. The thin-film transistor manufacturing method as described in item i of the patent application for the month of β, wherein the excimer laser is an argon fluoride laser. 9 The method for manufacturing a polycrystalline silicon of a thin film transistor as described in item 1 of the patent application scope, wherein the excimer laser is a xenon chloride laser. 10. The method for manufacturing polycrystalline silicon of a thin film transistor as described in item 1 of the scope of the patent application, wherein the temperature of the furnace tube annealing is about 550 to 60 (). 〇. 11. A method for manufacturing polycrystalline silicon of a thin film transistor, comprising: providing a substrate; depositing a first amorphous silicon layer on the substrate; irradiating the first amorphous silicon layer with an excimer laser to form a crystalline layer; Depositing a second amorphous silicon layer on the seed layer; and performing rapid thermal process annealing. 1 2. The method for manufacturing a thin film transistor as described in item 丨 丨 of the patent application scope further comprises: after providing the substrate, forming a buffer oxide layer on the substrate. 1 3. The method for manufacturing polycrystalline silicon of the thin film transistor according to item 11 of the scope of the patent application, wherein the substrate comprises a silicon substrate or a glass substrate. The thin-film manufacturing method described in item π of the patent scope, wherein the first non-Japanese silicon layer made of polycrystalline silicon is thinner than the second amorphous silicon layer. 15. According to the patent application method, the thickness of the first silicon layer is about 6 nanometers to 12 nanometers. ^ As described in the eleventh chapter of the patent application, the method of making thin-film electric body is made of polycrystalline silicon rice. The thickness of the second amorphous stone layer is about 30 nanometers to 15 nanometers. Ϊ: σΛ excimer laser system made of polycrystalline silicon made of thin crystalline silicon as described in item 11 above. It is a fluorinated gas laser. ^ Gu Tshen: The thin "transistor made of polycrystalline silicon /," and the excimer laser system described in item 11 of the scope of interest are argon fluoride lasers. U.S. Application: Thin-transistor polycrystalline silicon made of polycrystalline silicon as described in item 11 of the patent, where the excimer laser is a vaporized xenon laser. 20. The method for manufacturing a polycrystalline silicon thin film transistor as described in item 11 of the scope of patent application, wherein the annealing temperature in the rapid thermal process is about 600-750 ° C. Page 15