TW466569B - Method to anneal laterally grown polysilicon from amorphous silicon with patterned metal mask layer by pulse laser - Google Patents

Abstract

This invention provides the method to anneal laterally grown polysilicon from amorphous silicon with patterned metal cap layer by pulse laser. The procedures can be described as follows: providing a substrate; forming a amorphous silicon film layer on the substrate; forming a patterned metal mask layer on top of the amorphous silicon film layer; heating the substrate to maintain the temperature of the substrate within a temperature range; using laser to heat-treat the surface which creates a temperature gradient and thus converts the amorphous silicon film layer into laterally grown polysilicon; and ramping down the temperature.

Description

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V. Description of the Invention (i) Field of the Invention This case is a method for growing amorphous polycrystalline silicon by pulsed laser annealing with amorphous silicon using pulsed laser annealing, especially the method of crystalline silicon. Amorphous silicon with a metal-clad layer is grown laterally. BACKGROUND OF THE INVENTION Thin-film transistors are applicable to liquid crystal displays (Uquid p tranS1Str, TFT's)-.. Crystal display ϊγγ)) ^ Everything makes this product a The table y'LCD J is driven by personal computers, play instruments, κ =, .- mainstream products that do not steal. At present, because amorphous stone is the leading dominant product of the future, a-Si TFT, s, can be 200-300. ": Low-temperature growth, Yinbubu; Yu Yu, so broken widely used. However, the amorphous silicon (aS i) has a low electron mobility and does not go wrong] 0 / v exceeds 1 cm 2 / V. s' makes amorphous crystal thin film lightning crystals inadequate (highen j \- ,, And (nigh speed) το requirements for applications, and the crystalline silicon thin film transistor (pl0y_Si TFT, s) has a higher mobility (amorphous than the amorphous silicon thin film transistor (pl-y TFT's)) 2_3 orders of magnitude more), and low temperature sensitivity (10w temperature sensitivity), making it more suitable for high-speed components. When the amorphous silicon is conventionally annealed to form polycrystalline silicon, its formation temperature needs to be more than 600 ° C. Therefore, quartz is generally used as a substrate, but a glass substrate must be used in order to reduce costs. Therefore, the polycrystalline silicon formation temperature must be reduced to 500 ° C. 〇 or less. So ’many methods to reduce the temperature of polycrystalline silicon formation, such as excimer laser-induced crystalline (ELC), metal induced lateral crystallization (metal induced lateral

PD2034, ptd Page 4 4 6 6 5 6 9 V. Description of the Invention (2) The crystallization (MILC) method and metal induced crystallization (MLC) methods are widely discussed. Among them, when metal-induced crystallization is used to reduce the polycrystalline silicon formation temperature, the metal will contaminate the silicon after crystallization. This problem needs to be solved. The metal induced lateral crystallization (M I LC) method can avoid metal contamination and obtain larger silicon grains. Among them, when nickel (Ni) metal is used as a partial area covering metal, polycrystalline silicon grains without microtwin defects can be formed. When the component is applied, the metal (Ni) can be trapped at the source / drain, and at the same time as metal-induced lateral crystal growth is formed, metal silicide contacts are also formed. The excimer laser annealing method can raise the temperature of the amorphous silicon (aS i) film on the glass substrate to the melting point, without causing thermal damage to the glass substrate, and can form a high quality Polycrystalline silicon with low defect density. And compared with metal-induced lateral crystallization, its annealing time is short (nanoseconds), so polycrystalline silicon thin film transistors (poly-Si TFT's) are more suitable for active matrix liquid crystal display (active matrix liquid crystal display, AMLCDs) and static random access memories (SRAMs). However, when conventional excimer laser annealing is used, the polycrystalline silicon (ρ ο 1 y-S i) grains formed due to the rapid melting / solidification (me 1 t / sol idi f ication) of laser annealing. Smaller (about 100 η π or less), and smaller polycrystalline silicon (poly ~ Si) has a smaller electron mobility. Due to the lack of know-how, the applicant has carefully tested and researched the spirit of perseverance, and finally developed the "profit" of this case.

466569 V. Explanation of the invention (3) Pulsed laser annealing method for growing amorphous polysilicon with a metal-clad coating in the lateral direction. Brief Description of the Invention The main purpose of this case is to provide a method for laterally growing polycrystalline silicon by using pulse laser to anneal amorphous silicon with a patterned metal coating, so that it can be manufactured at low temperature (2 0 ~ 4 0 0 ° C). Polycrystalline silicon is formed, and the laterally grown grains can reach 1.0 ~ 2_0 " m. The steps include: providing a substrate; forming an amorphous stone film layer on the substrate; forming a metal overlay pattern layer on the amorphous stone film layer Heating the substrate to maintain the temperature of the substrate in a specific range, and irradiating the surface with a laser to 'form a temperature gradient' to convert the amorphous silicon thin film layer into laterally grown polycrystalline silicon, and then lowering the temperature. According to the above method, the substrate is selected from a glass substrate and a silicon substrate. According to the above conception, the amorphous silicon thin film layer is formed of an amorphous silicon (a-S i) material in the method. According to the above concept, the amorphous silicon material in the method is selected from the group consisting of positive amorphous silicon hydrogen (pa-Si: H), essential amorphous silicon hydrogen (ia-si: H), and negative amorphous silicon hydrogen (na -Si: H) and one or more of amorphous silicon germanium hydrogen (a_su-xGex: H). According to the above concept, the amorphous silicon thin film layer is deposited on the substrate by physical vapor deposition (E-gun) or sputter deposition. According to the above method, the amorphous sand film layer is reinforced with a plasma.

PD2034.ptd Page 6 466569 V. Description of the invention (4) A chemical enhanced chemical vapor deposition (PECVD) method is applied to the substrate. According to the above method, the metal of the metal overlay pattern layer is one of noble metal, near noble metal and refractory metal in the periodic table. According to the above concept, the metal overlay pattern layer is formed on the substrate by a lithography process and a physical vapor deposition method in the method. According to the above conception, the laser system in the method is an excimer laser. According to the idea, the excimer laser in the method is one or more of excimer lasers such as fluorinated gas (KrF), gasified gas (XeC1), argon fluoride (ArF), and gaseous krypton (XeF). According to the above conception, the depth of the melting zone in the method that is irradiated by the laser is adjusted by the laser energy density. G According to the above conception, the method scans the laser when the laser is irradiated. The irradiation is performed in the form of a light beam. "Product ... is caused by the difference in the laser energy of the amorphous silicon with the cover layer and the non-metallic metal-clad laser without the metal cover layer according to the above concept. In the evening, due to absorption according to the above-mentioned concept, the temperature of the substrate in the method is 200-400 t. The sacrifice system is based on the above-mentioned concept. In the method, the bottom of the substrate further includes-heating and crying to make the substrate The temperature is maintained in this specific range β Λ °°

ro2034.ptd Page 7 466569 V. Description of the invention (5) Please refer to the first figure (a) (b) (c), which uses pulse laser annealing for the lateral growth of amorphous silicon with a case-type metal coating. Schematic diagram of the process of polycrystalline seconds. The steps of this embodiment are: firstly providing a substrate i 0; secondly, a ore-amorphous stone film layer 11 on the substrate 10; then, a ore-metal covering pattern layer 12 on the amorphous silicon film layer 1 Then, the substrate 10 ′ is heated by a heater 13 and the temperature of the substrate 1G is maintained at 2i) () ~ 4〇 (rc :; finally, the surface is irradiated with a laser 14 to form a temperature After the gradient, the amorphous silicon thin film layer 11 is transformed into the laterally grown polycrystalline silicon 15, and then the temperature is lowered. The substrate 10 can choose one of a glass substrate and a second substrate. As for the amorphous silicon thin film layer 11, the amorphous silicon film layer 11 is made of amorphous silicon. (Amorphous Si, a-Si) material, and the amorphous silicon (a-Si) material may be selected from positive amorphous silicon hydrogen (p_a_Si. Η), essential amorphous silicon hydrogen (i-a-S i : Η), one or more of negative amorphous silicon hydrogen (n _ a ~ s main · Η) and amorphous stone hydrogen (a-Sil-xGex: H). 1¼ ^ The metal covers the pattern layer The metal system of 12 is one or more of noble metal, near noble metai, and refractory metal (refractory metal) in the periodic table. The excimer laser may be selected from one of excimer lasers such as krypton fluoride (KrF), gaseous xenon (XeCl), argon fluoride (ArF), and xenon fluoride (xeF). The depth of the melting ing zone is adjusted by the laser energy density. As for the laser energy & density range, 0.3 ~ 1_ 0 J / cm2 is better. When the laser irradiates a large area At ^, the irradiation is performed by scanning the laser beam. "

PD2034, ptd 466569 V. Description of the invention (6) Covered metal is formed between a wide range of amorphous stones and is formed by absorbing laser energy. The steps and methods for plating the amorphous silicon thin film layer 11 and the metal overlay pattern layer 2 are 'First, an electronic gun (E-gun) evaporation system is used at 300-400 ° C with a vacuum degree of 1-2x10. -6 Torr (Torr) conditions, or Plasma enhanced chemical vapor deposition (PECVD) method, at 250 ° C, base pressure (l-2xl0-6 Taoer ( Torr), pass in silane (SiH4) (20sccm) and hydrogen (H2) (25sccm) reaction gas, maintain the pressure to 1 Taoer (Torr), the power of 50W 'will be amorphous silicon (a-Si) or amorphous silicon hydrogen (a-Si: H), about 1500A 'is plated on the substrate. Then use the lithography process (1 i thography) and electronic evaporation deposition system, at room temperature, vacuum degree 1-2x10-6 Taoer!;! ^] :! ·), a metal film pattern is plated on the amorphous silicon film (as shown in the first figure (a)). Next, the substrate 10 is maintained at a temperature of 2 00 -400 ° C and a vacuum of 1-2x10-2 Torr, and is irradiated with an excimer laser 14 of an appropriate energy to make the amorphous silicon. (A-Si) is converted into polycrystalline silicon (poly-Si) '(as shown in the first graph (b) and (c)). After the excimer laser π is irradiated, the temperature is lowered immediately, and the holding time is about 10 minute. In summary, the present invention can effectively solve the problems of high temperature process, too long annealing time, etc. of the conventional technology, and achieve simple process and low process cost ', and the lateral growth of grains can reach 1. 〇 ~ 2, 0 # m 的The polycrystalline silicon thin film can be directly grown on a glass substrate to produce a low-cost integrated circuit (1C) device, which has industrial value and progress, and thus achieves the purpose of developing the present invention.

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PD2034.ptd Page 10 '46 656 9 Schematic illustration of the case The following figure and detailed description can be used to gain a deeper understanding: First picture (a) (b) (c): It is used in this case Schematic diagram of the side structure of pulsed laser annealing polysilicon lateral growth of amorphous silicon with a patterned metal coating. Description of drawing number i 0: substrate 11 · amorphous silicon thin film layer 1 2: metal cover pattern layer 1 3: warmer 15: laterally grown polycrystalline silicon 14: laser

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Claims (1)

6. Scope of patent application ^ ___ 1. A method for growing polycrystalline silicon by patterned metal coating using pulsed laser annealing, the steps include: forming a substrate of a layer of amorphous silicon in a layer; forming-an amorphous silicon thin film layer on On the substrate; forming a metal cover pattern layer on the amorphous silicon film to heat the substrate and maintaining the substrate temperature on the layer; and ~ a specific range; to irradiate the surface with a laser to form a temperature gradient, 俾 ▲ film The layer is converted into laterally grown polycrystalline silicon, and then it is subjected to falling / amorphous silicon thinning. 2. The method described in item 1 of the scope of the patent application, wherein the | ° glass substrate and the silicon substrate are one of. The κ soil plate system is selected from the method described in item 1 of the scope of the patent application, wherein the non-monolithic layer is formed of an amorphous stone (a m ◦ r p h 〇 s Si, a-S i) material. Xi's film 4. The method described in item 3 of the scope of patent application, wherein the amorphous U-Si) material is selected from positive amorphous silicon hydrogen (pa-Si: H) Said one or more of silicon hydrogen (bu a-Si: H), negative amorphous silicon hydrogen (na-Si: H) and amorphous silicon (a-Sil-xGex: H). 5. The method according to item 1 of the scope of patent application, wherein the amorphous silicon thin film layer is deposited on the substrate by a physical vapor deposition method. 6. The method according to item 1 of the scope of the patent application, wherein the amorphous silicon thin film layer is bonded to the substrate by a plasma enhanced chemical vapor deposition (PECVD) bonding film. 7 The method as described in item 1 of the scope of patent application, wherein the metal overlay PD2034.ptd Page 12 4 6 6 5 6 9 6. The metal layers of the patent application scope are noble metal, near noble metal and refractory metal in the periodic table. One or more. 8. The method according to item 1 of the scope of patent application, wherein the metal overlay pattern layer is formed on the substrate by a lithography process (1 i t h 0 g r a p h y) and a physical vapor phase bonding method. 9. The method according to item 1 of the scope of patent application, wherein the laser is an excimer laser. 10. The method according to item 9 of the scope of the patent application, wherein the excimer laser system is krypton fluoride (KrF), gaseous xenon (XeCl), argon fluoride (ArF) and xenon fluoride (XeF) Wait for one or more of the excimer lasers. 11. The method according to item 1 of the scope of patent application, wherein the depth of the melting zone irradiated by the laser is adjusted by the laser energy density. 1 2. The method according to item 1 of the scope of patent application, wherein when the laser irradiates a large area, the laser is irradiated by scanning the laser beam. 1 3. The method as described in item 1 of the scope of the patent application, wherein the temperature gradient is between amorphous silicon with a metal coating layer and amorphous silicon without a metal coating layer due to different absorption laser energy. Cause. 1 4. The method according to item 1 of the scope of patent application, wherein the specific range of the substrate temperature is 2 0-4 0 ° C. 1 5. The method according to item 1 of the scope of patent application, wherein a warmer is further included below the substrate to maintain the temperature of the substrate in the specific range. PD2034.ptd Page 13