TW473856B - Method for reducing particle contamination by controlling the polarity on the surface of wafer - Google Patents

Abstract

The present invention provides a method for reducing particle contamination by controlling the polarity on the surface of a wafer, which comprises: using oxygen-containing plasma ions to perform an in-situ bombardment on a damaged silicon substrate to reduce the magnitude of the contact angle between the particle and the surface of the silicon substrate when the particle is attached to the surface of the silicon substrate, in which the reasons of the surface of the silicon substrate being damaged include an ion implantation or etching procedure performed on this silicon substrate, and the silicon substrate being immersed into a particle cleaning tank to remove the polymer on the silicon substrate, in which the surface of the silicon substrate will form an oxide film layer in order to change the polarity on the surface of the silicon substrate into hydrophilic.

Description

473856 V. Description of the invention (i) Field of the invention: The present invention relates to a method for reducing particulate pollution, in particular, a method for controlling the surface polarity of a wafer to reduce particulate pollution. BACKGROUND OF THE INVENTION: In the semiconductor industry, the prevention and control of particulate contamination is a very important issue in wafer manufacturing of high-density integrated circuits. The current semiconductor industry has developed a number of methods to remove particles, such as: brush scrubbing; brush scrubber to remove particles, chemical washing methods using ultrasonic or mega sound sound disturbance systems to remove particles, Liquid, gas, or air is used to bombard the wafer surface to blow away or wash away particles and so on. There are many traditional methods of removing particulate pollution, such as "piasma processing system with reduced particle contamination" disclosed in U.S. Patent No. 5,557,357, and `` Ultra-low particle semiconductor cleaner for removal of particle contamination and disclosed in U.S. Patent No. 6004399. Residues from surface oxide formation on semi conductor wafers. There are several disadvantages to the traditional method of removing particulate pollution: (i) As most of the developed methods of removing particulates are physical removal

Page 4 473856 V. Description of the invention (2) ------ method, so when removing particles, it is easy to cause damage to the surface to be cleaned, and other particles are generated. (2) These developed methods for removing particulates must often be implemented after leaving the production line (0f f — ine). (3) These methods of removing particles that have been exhibited are usually implemented only after the wafer has been contaminated with particles. > In semiconductor manufacturing, one of the places where particulate contamination is often found is: the gate gap wall obtained after the engraving process, when it is immersed in a particle cleaning tank (for example: CR / STD (Caro's acid / standard) tank ), After the polymer cleaning stripping step, particulate contamination is often found near the gate gap. This particle composition is caused by the polarity effect of the silicon substrate and the poor cleaning efficiency of the particle cleaning tank, especially in high process run or severe substrate damage procedures. For example, the gap wall # 刻 程序. If this particle is found by a defect inspection machine (such as: 0m (optical microscope) or KLA (KLA-Kem detector manufactured by KLA-Tem〇 company, model KLA213x)), it can be It is cleared by using the CR / STD cleaning procedure again, but it will take more cost and longer cycle time. Let's take the first picture to the third picture as examples to briefly explain the reasons why the particle contamination is often found near the gate gap wall as follows. Please refer to the first picture, when a field oxide layer 1 2 and a gate structure 14

Page 5 473856 V. Description of the invention (3) After an insulating layer (such as an oxide layer) is deposited on the silicon substrate 10, the surface of the silicon substrate 10 will become a hydrophilic (hydrophobic 1 ic) silicon oxide ( S 1 _ 0) surface, at this time, if there are particles attached to the surface of the hydrophilic silicon oxide (Sl-0), the particles and the hydrophilic silicon oxide (hydr0Phillc) silicon oxide (with ―〇) The contact angle of the surface is about 8 degrees. Q >…, the first picture ^ After the gate gap wall remaining process is performed, part of the insulating layer 16 will be removed 'to form a gate gap wall 18 on two sides of the gate structure 14. At this time, the surface of the silicon substrate 10 will change from the surface of the hydrophilic silicon oxide (Si-O) to the surface of the draining (hydrophophic) Si Xi (Si-Si). If there are particles attached to the surface of the hydrophobic stone (Sl-Sl), the contact angle between the particles and the surface of the hydrophobic silicon (Si-Sl) is about 26. degree. Refer to the second figure, “Dip the wafer obtained after the gate spacer etching process” in a particle cleaning tank (eg, CR / STD (Car〇, s acid / standard) tank) for polymer cleaning. After the stripping step, theoretically, a chemical oxide will be formed on the silicon surface, so that the water-repellent stone surface becomes a hydrophilic silicon oxide surface, and thus no particles will adhere to the gate gap wall 18. However, due to the over-etching of plasma / ion implantation, the poor cleaning efficiency of the Shi Xi substrate or the particle cleaning tank caused the insufficient chemical oxide composition ’to cause the surface of the silicon substrate to be still a water-repellent silicon surface.

Page 6 473856 V. Description of the invention (4), so that it is on the gate. At this time, it is attached to the silicon contact angle (con tact again uses particulate acid / standard) ^ It costs a lot of cost and therefore, how to reduce the issue under urgent consideration after reconsideration.

Object and Summary of the Invention: The object of the present invention is a method for particle contamination by virtue of the problem of particle contamination. Another method of low particle pollution according to the present invention is to implant or #carve the program according to the steps of the present invention: (1) Use particles containing I near the partition wall 18, and particles 20 attached to the surface of Shi Xi's surface. The angle of the surface of the silicon substrate 10 is about 20 degrees. At present, it is usually removed by a cleaning tank (for example: CR / STD (Caro, s.) Cleaning procedure, but this will require a longer cycle time (cycU tiroe). It does not increase production costs and does not extend production time. The particle contamination on the wafer surface has become an industry expert, and he has been controlling the polarity of the wafer surface to reduce the polarity of the wafer surface to reduce the polarity of the wafer surface.

In order to reduce the surface polarity of the wafer, the polarity of the substrate is changed by changing the polarity of the substrate A + ^ L to repair the damaged wafer surface. The method proposed by L includes the following steps on the surface of a silicon substrate that has been damaged. 5. The size of the invention (5) angle), where the contact angle of the * surface (contact This silicon substrate is ionized) Contains a cleaning procedure for A particles, ^ t carved procedures. (2) #This Shixi substrate dipping ^ τ to remove this Shixi some Ma μ Xi take people & the surface of the substrate will form-oxide # ， 二 = , Its surface becomes hydrophilic (hydrophilic). "The surface of the surface of this substrate is in accordance with g_ 杳: > / r of the present invention: (1) forming a gate structure? The method of displaying the surface includes the following step formation layer on the interpolar structure and the surface of the Shixi substrate? Formation: Stepwise structure-side. (4) Use oxygen-containing electropolymeric ion to perform the same on the Shixi substrate -situ) bombardment to reduce the contact angle between the particles and the surface of the silicon substrate on the surface of the silicon substrate (contact) (5) immerse the silicon substrate in the particle cleaning tank to remove the poly delta on the silicon substrate An oxide film will be formed on the surface of the silicon substrate, so that the Shi Xi substrate The surface polarity becomes hydrophilic (hydrophiHc. In the above embodiment, the material of the oxide layer includes silicon oxide or tetraethyl silicate (TEOS). The electropolymer ion used for in-situ bombardment includes Oxygen 'in which simultaneous (in-sit u) bombardment consists of a pressure of about 75 0 ~ 850 mT, an energy of about 70 ~ 80 rF, and a duration of about 4 to 6 seconds with 30 sccm argon and 20 scCffl oxygen. The bombardment by a bell, and the preferred condition is a pressure of 473856. V. Description of the invention (6) Under 800mT and energy 75W, bombard with 300sccm argon and 20sccm oxygen for 5 seconds. Also, the particle cleaning tank contains CR / STD (C ar 〇 's ac id / standard) groove. In addition, the contact angle between the surface of the silicon substrate and the particles after the oxide layer is formed is about 7 to 9 degrees, and the silicon after the gate gap is formed. The contact angle between the surface of the substrate and the particles (contact ang 1 e) is about 2 4 to 28 degrees, and the contact angle between the surface of the substrate and the particles after the simultaneous (i η-situ) bombardment ) The size is about 8 ~ 1 2 degrees. The contact angle between the surface of the substrate and the particles is about 0 to 1 degree. Detailed description of the invention ... The purpose of the present invention is to provide a method for controlling the surface polarity of a wafer to reduce particle staining by changing the silicon substrate. To reduce the problem of particle contamination on the surface of the wafer. &Amp; Another object of the present invention is to provide a method to control the surface polarity of the wafer to reduce particle contamination. To repair wafer surfaces damaged by ion implantation or inscription processes. The invention is mainly characterized by the use of in-situ polarization correction

Page 9 473856 V. Description of the invention (7) The positive concept is that after the spacer etching process, the silicon substrate is synchronized with oxygen-containing plasma ions with a short processing time (preferably about 5 seconds) ( in-situ) bombardment to change the surface of the hydrophobic stone into a hydrophilic silicon oxide (Si-O) surface. In this way, as long as the surface of the hydrophi 1 ic silicon oxide (Si-0) is completely formed or partially formed, the particles in the particle cleaning tank (eg, CR / STD tank) or on other wet workbenches Contamination can be avoided or reduced. In addition, this method can be used in other programs where the surface of Shi Xi is engraved or damaged (such as ion implantation or engraving). The present invention uses the concept of polarity correction to change the polarity of the silicon substrate, and changes the polarity of the silicon substrate by using a plasma splash cleaning process to reduce the problem of particle contamination on the wafer surface. The present invention is described in detail in a preferred embodiment. First, referring to the fourth figure, a silicon substrate 30 is first provided, and then a known technique is used to sequentially form a field oxide layer 32 and a gate on the surface of the silicon substrate 30.极 结构 3 4 、 oxidation layer 36. The gate structure here may include a dioxide dioxide layer, a polycrystalline silicon layer, a tungsten silicide layer, a silicon nitride protective layer, and the like, and the material of the oxide layer 36 includes silicon oxide or tetraethyl silicate (TE 〇s). Since the above-mentioned process is made by the technology known in the past and is not the focus of the present invention, it will not be described in detail. It is worth mentioning that after the above-mentioned oxide layer 36 is formed, the surface of the Shixi substrate 30 will become a hydrophilic silicon oxide (S 1 -0) surface. At this time, if particles are attached to the hydrophilic property

Page 10 473856 V. Description of the invention (8) On the surface of silicon oxide (S i -0) (hydroph i 1 ic), the particles are on the surface of silicon oxide (si -〇) which is hydrophilic (hydroph i 1 ic) The contact angle is about 8 degrees. Then, referring to the fifth figure, a part of the oxide layer 36 is removed by using a conventional lithography etching technique to form a gate spacer wall 38 on two sides of the interelectrode structure 34. At this time, the surface of the Shi Xi substrate 30 after the gate electrode gap wall # engraving procedure will change from a hydrophilic oxidized stone Xi (Si-O) surface to a hydrophobic Si (Si-Si) surface At this time, if there are particles attached to the surface of the hydrophobic stone (Si-Si), then the particles and the surface of the hydrophobic stone (Si-S i) The contact angle is about 26 degrees. Next, please refer to the sixth figure, using a plasma ion containing oxygen to synchronize (i η-situ) 40 on the silicon substrate 3 0 for a short time, wherein the in-sit u bombardment 40 contains a pressure of about 750 At ~ 850 mT and energy of about 70 ~ 80 W, bombardment was performed with 300 sccm argon and 20 sccm oxygen for a duration of about 4 ~ 6 seconds. The preferred conditions are: bombarding with 300 s c c m argon and 20 s c c m oxygen for 5 seconds at a pressure of 800 mT and an energy of 75 rp. Here, after the silicon substrate 30 is bombarded by in-si tu for 40 seconds, the thickness of the silicon substrate 30 is very small, and the function of the device is not affected. Taking the above-mentioned preferred conditions of in-situ bombardment 40 as an example, each emulsification degree of the silicon substrate 30, p-layer 32, gate structure 34 and gate spacer 38 after bombardment is less than about 15 angstroms. At this time, although the surface of the silicon substrate 30 is still thick

473856 V. Description of the invention (9) (hydrophobic) silicon (Si-Si) surface, but if there are particles attached to the surface of the silicon substrate 30, the particles can be found in contact with the surface of the stone substrate 30 The contact angle has become significantly smaller (about 26 degrees to 10 degrees). Then, referring to the seventh figure, the silicon substrate 30 obtained after synchronizing (i η-situ) senso 40 was immersed in a particle cleaning tank (for example, a cr / std (Caro's acid / standard) tank). To perform a polymer stripping step. Chemical oxides will form on the silicon surface, making the water-repellent shredded surface a hydrophilic silicon oxide surface, so no particles will adhere to the gate spacers 18 and below. At this time, after the polymer cleaning stripping step, an oxide film layer 4 2 will be formed on the surface of the Shi Xi substrate 30, so that the hydrophobic silicon surface of the silicon substrate 30 will be partially or completely formed. Will turn into a hydrophilic (hydrophilic) silicon oxide (Si-〇) surface. At this time, no particles are attached to the surface of the silicon substrate 30 because the contact angle between the particles and the surface of the silicon substrate 30 has become approximately 0 degrees. Therefore, particle contamination in particle cleaning tanks (eg CR / STD tanks) or other thirsty workbenches can be avoided or reduced. … Then, the ion implantation step can be performed for the lightly doped drain / source heavily doped regions. _ Click on the cleaning procedure to change:

473856

Page 13 473856 Schematic description

The following descriptions and advantages have more A '! Ϊσ The following diagrams 丨' will help you understand the π of the present invention, where: The first picture is Fengdao u for beauty; + the cross section of the Japanese-Japanese film, Shows the steps of sequentially forming the point m and taking the emulsified layer, gate structure, and insulation layer on the noisy paper according to the traditional technology. The first figure is a cross-sectional view of the semiconducting headquarters on the 纟 saa sun-and-day film. ^ Yang Kai ^ The steps to form the gate gap on the two sides of the gate structure; ^ A picture is a cross-sectional view of a semiconductor wafer, and the rioter shows that the stone and soil are cleaned in a particulate cleaning tank (for example, according to traditional techniques) : CR / STD (Car0, s acid / standard) tank) for polymer cleaning; The fourth figure is a cross-sectional view of a semiconductor wafer, showing the sequential formation on a silicon substrate according to an embodiment of the present invention Field oxide layer, gate structure, and oxide layer steps. The fifth figure is a cross-sectional view of a semiconductor wafer, showing that according to an embodiment of the present invention, 'a portion of the insulation layer is removed, and a gate gap is formed on the gate structure. Steps on the two sides; the sixth picture is A cross-sectional view of a conductor wafer showing a step of in-situ bombarding a silicon substrate with oxygen-containing plasma ions for a short time according to an embodiment of the present invention; and the seventh diagram is a cross-sectional view of a semiconductor wafer It shows that according to an embodiment of the present invention, a silicon substrate is immersed in a particle cleaning tank (for example, a CR / STD (Caro's acid / standard) tank) to perform a polymer cleaning step.

473856 Schematic description of the drawing number part: broken substrate 10; field oxide layer 12; gate structure 14; insulating layer 16; gate spacer 18; particles 20; silicon substrate 30; field oxide layer 3 2; gate structure 3 4; oxide layer 36; gate spacer 3 8; in-situ bombardment 40; oxide film layer 4 2.

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Claims (1)

473856 6. Under the scope of patent application, bombardment with a length of about 4 to 6 seconds is performed with 300 sccm argon and 20 sccm m oxygen. 6. The method according to item 1 of the patent application range, wherein the above-mentioned in-situ bombardment includes bombardment at 300 sccm argon and 20 sccm oxygen for 5 seconds under a pressure of 800 mT and an energy of 75 W. 7. The method according to item 1 of the scope of patent application, wherein the above particle cleaning tank includes a CR / STD (Caro's acid / standard) tank. 8. The method according to item 1 of the scope of patent application, wherein the contact angle between the surface of the Shi Xi substrate and the particles after the formation of the oxide layer is about 7 to 9 degrees. 9. The method according to item 1 of the scope of patent application, wherein the contact angle between the surface of the δHai substrate and the particles after the formation of the gate gap is about 24 to 28 degrees. 10 · The method according to item 1 of the scope of patent application, wherein the contact angle between the surface of the silicon substrate and the particles after the in-situ bombardment is about 8-12 degrees. 11 · The method according to item 1 of the scope of patent application, wherein the contact angle between the surface of the silicon substrate and the particles after the Shi Xi substrate is immersed in the particle cleaning tank Page 17 473856 6. The size of the patent application (contact angle) is about ο ”degrees. 1 2 · A method for reducing particle contamination on the surface of the wafer, the method includes at least the following steps:-using oxygen-containing electropolyion In-situ bombardment of a silicon substrate with a damaged surface to reduce the size of the contact angle of the particles to the surface of the silicon substrate when the particles are attached to the surface of the silicon substrate. Reasons for the damage to the surface of the Shi Xi substrate include performing ion implantation or post-etching procedures on the silicon substrate; and immersing the Shi Xi substrate in a particle cleaning tank to remove the polymer on the silicon substrate, wherein the silicon substrate An oxide film layer will be formed on the surface, so that the surface polarity of the Shixi substrate becomes hydrophilic (hydrophi 1 ic). 1 3. The method according to item 丨 2 of the patent application range, in which the above-mentioned synchronization (in-si tu) The bombardment involves a bombardment with a pressure of about 75 0 to 850 mT and an energy of about 70 to 80 w with 300 sccm argon and 20 sccm oxygen for a period of about 4 to 6 seconds. 14 · If the scope of patent application Item 12 A method, wherein the above-mentioned in-situ bombardment includes bombardment under a pressure of 800 mT and an energy of 75 W, and bombardment with 300 sccm argon and 20 sccm oxygen for 5 seconds. The method, wherein the particle cleaning tank includes a CR / STD (Caro's acid / standard) tank. Page 18, 473856 6. Application scope of patent 16. The method according to item 12 of the scope of patent application, wherein the contact angle between the surface of the silicon substrate and the particles after the above-mentioned in-si tu bombardment (contact angle) About 8 ~ 12 degrees. 1 7. The method according to item 12 of the scope of patent application, wherein after the silicon substrate is immersed in the particle cleaning tank, the contact angle between the surface of the silicon substrate and the particles is about 0 to 1 degree. Page 19