JP2004235422A - Substrate peeling/cleaning method and manufacturing method of substrate for electro-optical apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure a sheet-fed cleaning, reduce the cost, and ensure cleaning harmless environmentally by employing as a peeling solution an aqueous oxalic acid solution at a low temperature with low concentration. <P>SOLUTION: The cleaning method is characterised by being provided with a process (step S23) for processing a substrate with the aqueous oxalic acid solution with a concentration of 1 to 10 % at a temperature of 30 to 50 °C. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for removing and cleaning a substrate suitable for removing an organic resist such as a liquid crystal substrate and a method for manufacturing an electro-optical device.
[0002]
[Prior art]
For example, a liquid crystal device is configured by sealing liquid crystal between two substrates such as a glass substrate and a quartz substrate. The structure of the liquid crystal device includes a passive type in which pixels are arranged in a matrix on the surface of a substrate, and a non-linear type such as a TFT (Thin Film Transistor) or a TFD (Thin Film Diode) for each pixel. An active element is provided in which an element is provided, and a signal electrode and a pixel electrode are connected via the non-linear element.
[0003]
In an active liquid crystal device, active elements are arranged in a matrix on one substrate, electrodes facing the other substrate are arranged, and the optical characteristics of a liquid crystal layer sealed between the two substrates are determined according to image signals. The image display is made possible by changing
[0004]
Such a TFT substrate is formed by repeating steps of cleaning, film formation, and pattern formation. In the pattern forming step, a photoresist is applied on a film of metal or the like formed on the inorganic body, and a fine pattern is formed by photolithography. Next, the entire surface of the semiconductor wafer is irradiated with UV light to cure the patterned resist film, thereby improving the dry etching resistance of the resist pattern. Thus, patterning is performed by dry-etching the non-mask region using the resist pattern as a mask.
[0005]
By the way, conventionally, organic solvents such as sulfuric acid peroxide and amines are used for stripping and cleaning of an organic resist used in a pattern forming step. In steps before the metal step, stripping and cleaning using sulfuric acid and hydrogen peroxide is performed. The resist formed on the surface of the semiconductor wafer is oxidized by the sulfuric acid and hydrogen peroxide to remove the resist on the wafer surface, attached particles, metal contaminants, and organic substances. In steps subsequent to the metal step, stripping cleaning using an organic solvent (organic stripper) is performed. Organic substances and resist can be removed by the dissolving action of the organic stripping solution. In this manner, the peeling process is performed without damaging the formed base pattern by utilizing the selectivity between the base film and the organic resist.
[0006]
In addition, the peeling cleaning using an organic solvent is disclosed in, for example, Patent Document 1.
[0007]
[Patent Document 1]
JP-A-10-256210
[Problems to be solved by the invention]
By the way, usually, a batch type cleaning apparatus is employed for stripping and cleaning the resist. However, a batch-type cleaning apparatus needs to prepare a plurality of cleaning tanks, and the apparatus scale is large, the occupied area is large, and the load on the equipment is extremely large. In the batch method, since the components of the stripping solution change relatively quickly, the replacement cycle of the stripping solution is short and the running cost is increased.
[0009]
In order to solve these drawbacks, it is conceivable to employ a single-wafer stripping / cleaning apparatus. However, in the case of using either sulfuric acid peroxide or an organic solvent, which is a stripping solution for an organic resist, it is necessary to heat these stripping solutions to about 100 ° C. and perform a dipping process for about 10 minutes during stripping and cleaning. That is, since it is necessary to use these harmful stripping liquids at a high temperature, a single-wafer type apparatus cannot be used as a stripping cleaning apparatus in consideration of durability, safety, and the like of a nozzle for supplying the stripping liquid. .
[0010]
When an organic solvent is used, explosion-proof specifications are indispensable. However, in a single wafer type spin cleaning apparatus, it is necessary to use a motor, and it is not possible to use an explosion-proof type. For these reasons, there has been a problem that a batch type stripping / cleaning apparatus requiring high apparatus cost and running cost and requiring a long cleaning time per sheet has to be adopted as a resist stripping apparatus. In addition, it is necessary to use harmful sulfuric acid and hydrogen peroxide and an organic solvent, which is not preferable from an environmental point of view.
[0011]
The present invention has been made in view of such problems, and enables the use of a single-wafer type stripping and cleaning apparatus by making it possible to use an oxalic acid aqueous solution having excellent safety as a stripping solution. An object of the present invention is to provide a method of removing and cleaning a substrate which is excellent in environment while reducing cost and running cost.
[0012]
[Means for Solving the Problems]
The substrate peeling and cleaning method according to the present invention includes a step of treating the substrate with an oxalic acid aqueous solution having a concentration of 1 to 10% and a temperature of 30 to 50 ° C.
[0013]
According to such a configuration, the organic resist on the substrate can be reliably peeled and cleaned by the oxalic acid aqueous solution. Since a low-concentration oxalic acid aqueous solution is used at a relatively low temperature, damage to a pipe for flowing the oxalic acid aqueous solution is small and the safety is high, so that it can be used in a single-wafer type peeling and cleaning apparatus. This makes it possible to reduce equipment, equipment costs and running costs, and also enables environmentally harmless peeling and cleaning.
[0014]
Further, before the step of treating with the oxalic acid aqueous solution, the method further comprises a step of completely removing the residual base material.
[0015]
According to such a configuration, the organic resist and the underlying material remaining in the organic resist can be completely removed.
[0016]
Further, the step of completely removing the residual base material is realized by an ashing process using O ₂ plasma.
[0017]
According to such a configuration, the residual base material can be reliably removed without using a harmful chemical solution.
[0018]
A rinsing step of rinsing the substrate treated with the oxalic acid aqueous solution using a rinsing liquid is further provided.
[0019]
According to such a configuration, the organic resist peeled from the substrate can be reliably removed from the substrate surface by the rinsing liquid.
[0020]
The rinsing liquid is pure water or isopropyl alcohol.
[0021]
According to such a configuration, the organic resist can be reliably removed.
[0022]
The method may further include a drying step of drying the substrate after the rinsing step.
[0023]
According to such a configuration, the organic resist can be reliably removed without causing cleaning stains or the like.
[0024]
Further, at least one of the step of treating with the oxalic acid aqueous solution, the rinsing step, and the drying step is performed using a single-wafer spin apparatus that rotates one substrate.
[0025]
According to such a configuration, the organic resist can be reliably removed from the substrate by the centrifugal force accompanying the rotation of the substrate, and the time required for drying can be reduced.
[0026]
Further, the substrate is a substrate for an electro-optical device.
[0027]
According to such a configuration, it can be applied to a substrate of an electro-optical device such as a liquid crystal device, an EL (electroluminescence) device, and an electrophoresis device.
[0028]
In the method of manufacturing an electro-optical device according to the present invention, the step of treating the layer to be laminated on the electro-optical device substrate with an aqueous oxalic acid solution having a concentration of 1 to 10% and a temperature of 30 to 50 ° C. It is characterized by having.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a flowchart showing a substrate peeling and cleaning method according to the first embodiment of the present invention. FIG. 2 is an equivalent circuit diagram of various elements, wiring, and the like in a plurality of pixels forming a pixel region of a TFT substrate (element substrate) as a substrate to which the present embodiment is applied. FIG. 3 is a plan view of a liquid crystal device using an element substrate to which the present embodiment is applied, and is a plan view together with each component formed on the element substrate as viewed from the counter substrate side. FIG. 4 is a cross-sectional view of the liquid crystal device after the assembly step of bonding the element substrate and the counter substrate and enclosing the liquid crystal after completion of the assembly process, taken along the line HH 'in FIG. FIG. 5 is a sectional view showing the liquid crystal device of FIGS. 3 and 4 in detail. FIG. 6 is a flowchart showing a substrate process of the element substrate. FIG. 7 is an explanatory view showing a substrate peeling cleaning method using spin cleaning.
[0030]
This embodiment is based on the premise that full-ashing (complete ashing process) using O ₂ plasma or the like is performed on the removal of an organic resist, using an aqueous solution containing oxalic acid, which is a carboxylic acid, at a relatively low temperature as a removal cleaning solution. By performing the cleaning, not only a batch type but also a single wafer type peeling and cleaning apparatus can be used, thereby reducing the apparatus cost and the running cost and also enabling environmentally excellent peeling and cleaning.
[0031]
First, with reference to FIGS. 2 to 5, a structure of a liquid crystal device using an element substrate to be peeled and cleaned in this embodiment will be described.
[0032]
As shown in FIGS. 3 and 4, the liquid crystal device, which is an electro-optical device, is configured by sealing a liquid crystal 50 between an element substrate 10 such as a TFT substrate and a counter substrate 20. Pixel electrodes and the like constituting pixels are arranged in a matrix on the element substrate 10. FIG. 2 shows an equivalent circuit of an element on the element substrate 10 that constitutes a pixel.
[0033]
As shown in FIG. 2, in the pixel area, a plurality of scanning lines 3a and a plurality of data lines 6a are wired so as to intersect with each other, and a pixel electrode is formed in an area defined by the scanning lines 3a and the data lines 6a. 9a are arranged in a matrix. Then, a TFT 30 is provided corresponding to each intersection of the scanning line 3a and the data line 6a, and the pixel electrode 9a is connected to the TFT 30.
[0034]
The TFT 30 is turned on by the ON signal of the scanning line 3a, whereby the image signal supplied to the data line 6a is supplied to the pixel electrode 9a. A voltage between the pixel electrode 9 a and the counter electrode 21 provided on the counter substrate 20 is applied to the liquid crystal 50. In addition, a storage capacitor 70 is provided in parallel with the pixel electrode 9a, and the storage capacitor 70 allows the voltage of the pixel electrode 9a to be held for a time that is, for example, three digits longer than the time during which the source voltage is applied. The storage capacitor 70 improves voltage holding characteristics and enables image display with a high contrast ratio.
[0035]
FIG. 5 is a schematic cross-sectional view of a liquid crystal device focusing on one pixel.
[0036]
A groove 11 is formed in an element substrate 10 such as glass or quartz. On the groove 11, a TFT 30 having an LDD structure is formed via a light shielding film 12 and a first interlayer insulating film 13. The groove 11 flattens the boundary surface between the TFT substrate and the liquid crystal 50.
[0037]
The TFT 30 includes a semiconductor layer having a channel region 1a, a source region 1d, and a drain region 1e provided with a scanning line 3a serving as a gate electrode via lower and upper insulating films 2a and 2b. The light-shielding film 12 is formed in a region corresponding to the formation region of the TFT 30, a formation region of the data line 6a and the scanning line 3a described later, that is, a region corresponding to a non-display region of each pixel. The light shielding film 12 prevents reflected light from entering the channel region 1a, the source region 1d, and the drain region 1e of the TFT 30.
[0038]
A second interlayer insulating film 14 is stacked on the TFT 30, and an intermediate conductive layer 15 is formed on the second interlayer insulating film 14. A capacitance line 18 is disposed on the intermediate conductive layer 15 with a dielectric film 17 interposed therebetween. The capacitance line 18 is composed of a capacitance layer and a light-shielding layer, forms a storage capacitance with the intermediate conductive layer 15, and has a light-shielding function of preventing internal reflection of light. Since the intermediate conductive layer 15 is formed at a position relatively close to the semiconductor layer, diffused reflection of light can be efficiently prevented.
[0039]
A third interlayer insulating film 19 is arranged on the capacitance line 18, and the data line 6 a is stacked on the third interlayer insulating film 19. The data line 6a is electrically connected to the source region 1d through contact holes 24a and 24b penetrating the third and second interlayer insulating films 19 and 14. The pixel electrode 9a is stacked on the data line 6a via the fourth interlayer insulating film 25. The pixel electrode 9a is electrically connected to the drain region 1e via the capacitance line 18 by contact holes 26a, 26b penetrating the fourth and second interlayer insulating films 25, 19, 14. An alignment film 16 made of a polyimide-based polymer resin is laminated on the pixel electrode 9a and rubbed in a predetermined direction.
[0040]
When an ON signal is supplied to the scanning line 3a (gate electrode), the channel region 1a becomes conductive, the source region 1d and the drain region 1e are connected, and the image signal supplied to the data line 6a is supplied to the pixel electrode 9a.
[0041]
On the other hand, the opposing substrate 20 is provided with a first light-shielding film 23 in a region facing the data line 6a, the scanning line 3a, and the region where the TFT 30 is formed on the TFT array substrate, that is, a non-display region of each pixel. The first light-shielding film 23 prevents incident light from the counter substrate 20 from entering the channel region 1a, the source region 1d, and the drain region 1e of the TFT 30. A counter electrode (common electrode) 21 is formed over the entire surface of the substrate 20 on the first light shielding film 23. An alignment film 22 made of a polyimide polymer resin is laminated on the counter electrode 21 and rubbed in a predetermined direction.
[0042]
Then, a liquid crystal 50 is sealed between the element substrate 10 and the counter substrate 20. Thus, the TFT 30 writes the image signal supplied from the data line 6a to the pixel electrode 9a at a predetermined timing. In accordance with the written potential difference between the pixel electrode 9a and the counter electrode 21, the orientation and order of the molecular assembly of the liquid crystal 50 are changed, thereby modulating light and enabling gray scale display.
[0043]
As shown in FIGS. 3 and 4, the opposing substrate 20 is provided with a light-shielding film 42 as a frame for dividing a display area. The light shielding film 42 is formed of, for example, the same or different light shielding material from the light shielding film 23.
[0044]
A sealing material 41 for enclosing liquid crystal is formed between the element substrate 10 and the counter substrate 20 in a region outside the light shielding film 42. The sealing material 41 is disposed so as to substantially match the contour shape of the counter substrate 20, and fixes the element substrate 10 and the counter substrate 20 to each other. The sealing material 41 is missing on a part of one side of the element substrate 10, and a liquid crystal injection port 78 for injecting the liquid crystal 50 is formed in a gap between the bonded element substrate 10 and the counter substrate 20. You. After the liquid crystal is injected from the liquid crystal injection port 78, the liquid crystal injection port 78 is sealed with a sealing material 79.
[0045]
A data line drive circuit 61 and a mounting terminal 62 are provided along a side of the element substrate 10 in a region outside the sealing material 41 of the element substrate 10, and a scanning line is formed along two sides adjacent to the one side. A drive circuit 63 is provided. On one remaining side of the element substrate 10, a plurality of wirings 64 for connecting the scanning line driving circuits 63 provided on both sides of the screen display area are provided. In at least one of the corners of the opposing substrate 20, a conductive material 65 for electrically connecting the element substrate 10 and the opposing substrate 20 is provided.
[0046]
Next, a manufacturing process of the element substrate configured as described above will be described with reference to a flowchart of FIG.
[0047]
First, a TFT array substrate 10 such as a quartz substrate, hard glass, or silicon substrate is prepared. The prepared substrate 10 is annealed, preferably in an inert gas atmosphere such as N ₂ (nitrogen) and at a high temperature of about 900 to 1300 ° C., so that distortion generated in the TFT array substrate 10 in a high-temperature process performed later is small. Pre-process so that
[0048]
Next, in step S1 of FIG. 6, a groove 11 (see FIG. 5) is formed in the TFT array substrate 10 by etching or the like. That is, an organic resist is applied to the surface of the substrate 10, and a fine pattern is formed on the organic resist by photolithography. Next, the entire surface of the substrate 10 is irradiated with UV light to cure the patterned organic resist, thereby improving the dry etching resistance of the resist pattern. The non-mask region is dry-etched using the resist pattern as a mask. Thus, a patterned groove 11 is formed.
[0049]
In the present embodiment, the organic resist used for forming the pattern of the groove 11 is peeled and cleaned based on a flowchart of FIG. 1 described later. Next, in step S2 of FIG. 6, a metal such as Ti, Cr, W, Ta, Mo, and Pd or a metal alloy film such as a metal silicide is formed by sputtering to a thickness of about 100 to 500 nm, preferably about 200 nm. Deposit to a film thickness. Then, the lower light-shielding film 12 having a lattice-like planar shape is formed by photolithography and etching. Also at the time of forming the pattern of the lower light-shielding film 12 in step S2, the organic resist is peeled and cleaned according to the flow of FIG.
[0050]
Next, in Step S3, a TEOS (tetra-ethyl-ortho-silicate) gas, a TEB (tetra-ethyl-borate) gas, and a TMOP ( The interlayer insulating film 13 made of a silicate glass film such as NSG, PSG, BSG, BPSG, or the like, a silicon nitride film, a silicon oxide film, or the like is formed using a tetramethyl oxyphosphate (gas). The thickness of the interlayer insulating film 13 is, for example, about 500 to 2000 nm.
[0051]
Next, in step S4, low pressure CVD using monosilane gas, disilane gas, or the like at a flow rate of about 400 to 600 cc / min in a relatively low temperature environment of about 450 to 550 ° C., preferably about 500 ° C., on the interlayer insulating film 13. An amorphous silicon film is formed by (for example, CVD at a pressure of about 20 to 40 Pa). Thereafter, the polysilicon film is annealed in a nitrogen atmosphere at about 600 to 700 ° C. for about 1 to 10 hours, preferably for 4 to 6 hours, so that the polysilicon film has a particle size of about 50 to 200 nm, preferably Solid phase growth is performed until the particle size becomes about 100 nm. As a method for solid phase growth, annealing treatment using RTA (Rapid Thermal Anneal) or laser annealing using excimer laser or the like may be used. At this time, depending on whether the pixel switching TFT 30 is of an n-channel type or a p-channel type, a dopant of a group V element or a group III element may be slightly doped by ion implantation or the like. Then, a semiconductor layer 1a having a predetermined pattern is formed by photolithography and etching. It should be noted that the organic resist is also removed in accordance with the flow of FIG. 1 during the pattern formation of the semiconductor layer 1a.
[0052]
Next, in step S5, the semiconductor layer 1a constituting the TFT 30 is thermally oxidized at a temperature of about 900 to 1300 ° C., preferably at a temperature of about 1000 ° C., and then continuously performed by a low pressure CVD method or the like, Thereby, the lower and upper gate insulating films 2a and 2b (including the gate insulating film) made of a multilayer high-temperature silicon oxide film (HTO film) and a silicon nitride film are formed.
[0053]
As a result, the semiconductor layer 1a has a thickness of about 30 to 150 nm, preferably about 35 to 50 nm, and the insulating films 2a and 2b have a thickness of about 20 to 150 nm, preferably about 30 to 150 nm. The thickness is 100 nm.
[0054]
Next, in order to control the threshold voltage Vth of the pixel switching TFT 30, a predetermined amount of a dopant such as boron is doped into the N-channel region or the P-channel region of the semiconductor layer 1a by ion implantation or the like. I do.
[0055]
Next, in step S6, a polysilicon film is deposited by a low pressure CVD method or the like, and phosphorus (P) is thermally diffused to make the polysilicon film conductive. Alternatively, a doped silicon film in which P ions are introduced simultaneously with the formation of the polysilicon film may be used. The thickness of the polysilicon film is about 100 to 500 nm, preferably about 350 nm. Then, a scanning line 3a having a predetermined pattern including the gate electrode portion of the TFT 30 is formed by photolithography and etching. Even when the pattern of the scanning line 3a is formed, the organic resist is peeled and cleaned in accordance with the flow of FIG.
[0056]
For example, when the TFT 30 is an n-channel TFT having an LDD structure, the scanning line 3a (gate electrode) is used as a mask to form a low-concentration source region and a low-concentration drain region in the semiconductor layer 1a. , P, etc. at a low concentration (for example, P ions at a dose of 1 to 3 × 10 ¹³ / cm ² ) (step S7). Thus, the semiconductor layer 1a below the scanning line 3a becomes the channel region 1a '.
[0057]
Further, in order to form the high-concentration source region 1d and the high-concentration drain region 1e constituting the pixel switching TFT 30, a resist layer having a plane pattern wider than the scanning line 3a is formed on the scanning line 3a. Thereafter, a dopant of a group V element such as P is doped at a high concentration (for example, P ions are doped at a dose of 1 to 3 × 10 ¹⁵ / cm ² ) (step S8).
[0058]
Thus, an element having an LDD structure having low-concentration source / drain regions and high-concentration source / drain regions is formed. Note that, for example, a TFT having an offset structure may be used without performing low-concentration doping, and a self-aligned TFT may be formed by an ion implantation technique using P ions, B ions, or the like using the scanning line 3a as a mask. The resistance of the scanning line 3a is further reduced by the impurity doping.
[0059]
Next, in step S9, a silicate glass film such as NSG, PSG, BSG, BPSG, or the like is formed on the scanning line 3a by using, for example, a TEOS gas, a TEB gas, a TMOP gas, or the like by normal pressure or reduced pressure CVD. A second interlayer insulating film 14 made of a silicon film, a silicon oxide film, or the like is formed. The thickness of the second interlayer insulating film 14 is, for example, about 500 to 2000 nm. Here, preferably, annealing is performed at a high temperature of about 800 ° C. to improve the film quality of the interlayer insulating film 14.
[0060]
Next, in step S10, the contact holes 24a and 26a are simultaneously opened by dry etching such as reactive ion etching and reactive ion beam etching on the second interlayer insulating film 14. Even when the contact holes 24a and 26a are formed, the organic resist is peeled and cleaned according to the flow of FIG.
[0061]
Next, in step S11, the first intermediate conductive layer 15 that becomes the lower capacitance electrode of the storage capacitor is formed. That is, a polysilicon film is deposited on the second interlayer insulating film 14 by a low-pressure CVD method or the like, and phosphorus (P) is thermally diffused to make the polysilicon film conductive. Alternatively, a doped silicon film in which P ions are introduced simultaneously with the formation of the polysilicon film may be used. The thickness of the polysilicon film is about 100 to 500 nm, preferably about 150 nm. Then, patterning is performed by photolithography and etching to form the first intermediate conductive layer 15. Even when the intermediate conductive layer 15 is formed, the organic resist is removed and washed according to the flow of FIG.
[0062]
In the next step S12, a dielectric film 17, which is an insulating film of the storage capacitor, is formed. That is, a dielectric made of a high-temperature silicon oxide film (HTO film) or a silicon nitride film is formed on the first intermediate conductive layer 15 and the second interlayer insulating film 14 also serving as a pixel potential side capacitor electrode by a low pressure CVD method, a plasma CVD method, or the like. The film 17 is deposited to a relatively small thickness of about 50 nm.
[0063]
The dielectric film 17 may be composed of either a single-layer film or a multilayer film, as in the case of the insulating films 2a and 2b, and various known films generally used for forming a gate insulating film of a TFT. It can be formed by technology. Since the storage capacity increases as the dielectric film 17 becomes thinner, the dielectric film 17 becomes an extremely thin insulating film having a thickness of 50 nm or less on condition that no defects such as film breakage occur. It is advantageous to form
[0064]
Next, in step S13, a capacitance line 18 is formed on the dielectric film 17. The film thickness of the capacitance line 18 is set to, for example, 150 nm.
[0065]
Next, in step S14, a third interlayer insulating film made of a silicate glass film such as NSG, PSG, BSG, or BPSG, a silicon nitride film, a silicon oxide film, or the like is formed by using, for example, a normal pressure or reduced pressure CVD method or a TEOS gas. A film 19 is formed. The thickness of the third interlayer insulating film 19 is, for example, about 500 to 1500 nm.
[0066]
Next, in step S15, a low-resistance metal such as Al or a metal silicide having a light-shielding property is formed as a metal film by sputtering or the like on the entire surface of the third interlayer insulating film 19 so as to fill the contact holes 24a and 24b. Deposit to a thickness of 100-500 nm, preferably about 300 nm. Then, the data line 6a having a predetermined pattern is formed by photolithography and etching (Step S16). Also at the time of forming the data line 6a, the organic resist is peeled and cleaned according to the flow of FIG.
[0067]
Next, in step S17, a silicate glass film such as NSG, PSG, BSG, BPSG, or the like, a silicon nitride film, or an oxidized film is formed so as to cover the data line 6a by using, for example, normal pressure or reduced pressure CVD, TEOS gas, or the like. A fourth interlayer insulating film 25 made of a silicon film or the like is formed. The thickness of the fourth interlayer insulating film 25 is, for example, about 500 to 1500 nm.
[0068]
Next, in step S18, a contact hole 26b is formed by dry etching such as reactive ion etching or reactive ion beam etching on the fourth interlayer insulating film 25 and the third interlayer insulating film 19. Even when the contact hole 26b is formed, the organic resist is peeled and cleaned according to the flow of FIG.
[0069]
Next, in step S19, a transparent conductive film such as an ITO film is deposited on the inner peripheral surface of the contact hole 26b and the fourth interlayer insulating film 25 by sputtering or the like to a thickness of about 50 to 200 nm. . Then, the pixel electrode 9a is formed by photolithography and etching. When the liquid crystal device is used for a reflection type liquid crystal device, the pixel electrode 9a may be formed from an opaque material having a high reflectance such as Al (aluminum). The contact hole 26b connects the first intermediate conductive layer 15 and the pixel electrode 9a. Also during the formation of the pixel electrode 9a, the organic resist is peeled and cleaned according to the flow of FIG.
[0070]
Next, peeling cleaning performed at the time of patterning at the time of forming each film will be described with reference to the flowchart of FIG. 1 and the explanatory diagram of FIG.
In this embodiment mode, not only a batch type peeling / cleaning apparatus but also a single-wafer type peeling / cleaning apparatus can be used as the apparatus used for the peeling / cleaning. FIG. 7 shows such a single-wafer stripping / cleaning apparatus. The substrate peeling and cleaning apparatus 70 is provided with a spin chuck 71 as a turntable that is rotated by a driving device (not shown) so as to be rotatable in a horizontal plane. On the spin chuck 71, a substrate 72 is placed with its surface being horizontal. The spin chuck 71 suction-holds the back surface of the substrate 72 by vacuum suction.
[0071]
Above the spin chuck 71, nozzles 73 and 76 for supplying a stripping cleaning liquid or the like for cleaning the substrate 72 to the surface of the substrate 72 can be provided. The nozzles 73 and 76 are configured such that the discharge ports at the tips are arranged near the surface of the substrate 72. Thus, the nozzles 73 and 76 can discharge the cleaning liquid or the like and spray the liquid directly onto the substrate 72. The nozzles 73 and 76 can also discharge a stripping cleaning liquid or the like while scanning horizontally on a plane parallel to the surface of the substrate 72.
[0072]
In the present embodiment, the nozzle 73 is for discharging an oxalic acid aqueous solution, and the nozzle 76 is for discharging isopropyl alcohol or pure water. The nozzles 73 and 76 can selectively spray an oxalic acid aqueous solution as a stripping cleaning liquid, isopropyl alcohol or pure water as a rinsing liquid onto the substrate 72 for an appropriate time.
[0073]
Due to the centrifugal force generated by the rotation of the substrate 72, the stripping cleaning liquid or the like discharged onto the substrate 72 flows on the substrate 72 with sufficient force in the centrifugal direction from the center of rotation and flows out on the surface of the substrate 72. It has become.
[0074]
In stripping and cleaning of the organic resist, first, in step S21 of FIG. 1, full ashing using O ₂ plasma is performed. Conventionally, in the steps subsequent to the metal step, an amine-based organic solvent has been used as a resist stripper as described above in order not to dissolve the underlying metal layer. By dry etching using ions for the underlying film to be patterned, the underlying film chemically reacts and gasifies. The gasified base film material is implanted into the resist by ions. The residual inorganic substance thus implanted (hereinafter referred to as a deposited polymer) cannot be removed with an organic solvent. For this reason, conventionally, the deposited polymer is removed by mixing ammonium fluoride or the like with an organic solvent.
[0075]
On the other hand, in the present embodiment, the organic solvent is not used, and the deposited polymer is first completely removed by full ashing using an O ₂ plasma apparatus.
[0076]
Next, the organic resist from which the deposited polymer has been completely removed is transported onto the spin chuck 71 and adsorbed (step S22). Next, in step S23, spin cleaning using oxalic acid is performed. Note that the stripping cleaning liquid is not limited to the oxalic acid aqueous solution, and various chemicals containing carboxylic acid can be used. The carboxylic acid may be a carboxylic acid having a carboxyl group, such as a monocarboxylic acid or a polycarboxylic acid, or a substituted carboxylic acid such as an oxycarboxylic acid, an aminocarboxylic acid, a ketone carboxylic acid, or an aldehyde carboxylic acid. it can. Specifically, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, lauric acid, palmitic acid, aliphatic monocarboxylic acids such as stearic acid, oxalic acid, malonic acid, succinic acid, maleic acid, glutaric acid, adipic acid, Aliphatic polycarboxylic acids such as sebacic acid; aromatic monocarboxylic acids such as benzoic acid and toluic acid; aromatic polycarboxylic acids such as phthalic acid and trimellitic acid; oxyacids such as glycolic acid, malic acid, tartaric acid, and citric acid Examples thereof include ketone carboxylic acids such as carboxylic acid, pyruvic acid and levulinic acid, aldehyde carboxylic acids such as glyoxylic acid, and amino acids such as glycine and alanine. One or more of these acids may be used in combination.
[0077]
The tank 74 stores an oxalic acid aqueous solution. The concentration of the aqueous oxalic acid solution is 1 to 10%, and the temperature is set to 30 to 50C. For example, a 5% oxalic acid aqueous solution having a temperature of about 40 ° C. is supplied from the tank 74 to the nozzle 73, and is discharged from the discharge port of the nozzle 73 toward the surface of the substrate 72. Since an aqueous solution of oxalic acid having a relatively low temperature and a low concentration is used as the stripping solution, the supply pipe for the stripping solution is not damaged, and a single-wafer apparatus can be employed. When an aqueous oxalic acid solution is used, explosion-proof specifications are not an essential requirement, and a single-wafer type device can be used from this point of view.
[0078]
While rotating the substrate 72 by rotating the spin chuck 71, an oxalic acid aqueous solution is sprayed from the nozzle 73 onto the substrate surface. By spin-cleaning for about 2 minutes in this state, the organic resist on the base film is removed from the surface of the substrate 72. FIG. 7A shows this state. In this case, the aqueous solution of oxalic acid discharged from the discharge port of the nozzle 73 vigorously flows in the centrifugal direction from the center of the substrate 72 by the action of the centrifugal force generated by the rotation of the spin chuck 71. Due to such a flow of the stripping solution, the organic resist on the substrate 72 is stripped off from the substrate 72, is washed away to the periphery, and is removed from the substrate 72. The aqueous oxalic acid solution that has flowed down from the surface of the substrate 72 is collected by the cup member 75, returned to the tank 74, and circulated.
[0079]
Next, in step S24, rinsing using a rinsing liquid such as pure water or isopropyl alcohol is performed. That is, a rinsing liquid such as pure water is discharged from the discharge port of the nozzle 76 toward the surface of the substrate 72. This rinsing is performed for about 30 seconds to 1 minute. FIG. 7B shows this state. Also in this case, the rinsing liquid discharged from the nozzle 76 vigorously flows in the centrifugal direction from the center of the substrate 72 by the action of the centrifugal force generated by the rotation of the spin chuck 71. Due to the flow of the rinsing liquid, the organic resist peeled off from the substrate 72 is flushed around the substrate 72 and is surely removed from the substrate 72.
[0080]
Finally, in step S25, spin drying is performed. FIG. 7C shows this state, and the drying step is performed for about 1 minute. Although the substrate 72 is simply spun in FIG. 7C, the drying time can be further shortened by flowing out N ₂ gas from a nozzle (not shown) and spraying the N ₂ gas on the surface of the substrate 72. It is.
[0081]
As described above, in the present embodiment, a batch-type stripping and cleaning apparatus was used for stripping the organic resist after patterning of various films by using an aqueous solution of 1 to 10% oxalic acid heated to 50 ° C. or lower. In addition to the peeling cleaning by the dip processing, the peeling cleaning by the single wafer spin processing using the single wafer type peeling cleaning apparatus is enabled. As a result, the cost of the factory equipment can be reduced, and the running cost can be reduced since the stripping solution does not need to be wastefully discarded in the single-wafer method. The deposited polymer after metal dry etching, which was conventionally difficult to peel, is also reliably peeled and cleaned by a spin-oxalic acid treatment at 45 ° C. for 2 minutes, a pure water rinse, and a spin-drying step of 4 minutes or less per sheet. be able to. Thereby, the throughput can be improved, and peeling in one cycle can be performed. A low-temperature, low-concentration oxalic acid aqueous solution is used instead of sulfuric acid-hydrogen peroxide and organic substance stripper, which can reduce the initial cost of factory equipment and the running cost during wafer processing, and is also environmentally-friendly. Washing is possible.
[0082]
Further, in the above-described embodiment, an example in which the present invention is applied to resist removal after dry etching has been described. However, it is apparent that the present invention is similarly applicable to resist removal after wet etching.
[0083]
Further, in the above-described embodiment, the peeling cleaning at the time of film formation of the pixel region in the TFT substrate of the liquid crystal device has been described. It is clear that is also applicable. Further, the present invention can be applied to a display panel such as an EL (electroluminescence) device and an electrophoresis device. Further, the present invention is not limited to a liquid crystal substrate, and may be used at the time of various film formation using an organic resist such as a semiconductor substrate. Obviously, it is applicable to cleaning.
[0084]
Although FIG. 7 illustrates an example in which the present invention is applied to a single-wafer type peeling and cleaning apparatus, the present invention is also applicable to a batch type peeling and cleaning apparatus using an oxalic acid aqueous solution and a rinsing liquid.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a substrate peeling and cleaning method according to a first embodiment of the present invention.
FIG. 2 is an equivalent circuit diagram of various elements, wiring, and the like in a plurality of pixels forming a pixel region of a TFT substrate (element substrate) which is a semiconductor device to which the present embodiment is applied;
FIG. 3 is a plan view of a liquid crystal device using an element substrate to which the present embodiment is applied, as viewed from a counter substrate side together with components formed on the element substrate.
FIG. 4 is a cross-sectional view of the liquid crystal device after the assembly step of bonding an element substrate and a counter substrate and enclosing liquid crystal after completion of the assembly process, taken along the line HH ′ in FIG. 3;
FIG. 5 is a cross-sectional view showing the liquid crystal device of FIGS. 3 and 4 in detail.
FIG. 6 is a flowchart showing a substrate process of an element substrate.
FIG. 7 is an explanatory view showing a substrate peeling cleaning method using spin cleaning.
[Explanation of symbols]
S21: Full ashing step S22: Transport step 23: Spin cleaning step with oxalic acid 24: Rinse step S25: Drying step

Claims (9)

A method for removing and cleaning a substrate, comprising a step of treating the substrate with an aqueous oxalic acid solution having a concentration of 1 to 10% and a temperature of 30 to 50 ° C. The method according to claim 1, further comprising a step of completely removing a residual base material before the step of treating with the oxalic acid aqueous solution. Process, the substrate peeling cleaning method according to claim 2, characterized in that is realized by ashing treatment with O ₂ plasma to completely remove the residual substrate material. The substrate peeling and cleaning method according to claim 1, further comprising a rinsing step of rinsing the substrate treated with the oxalic acid aqueous solution using a rinsing liquid. The method according to claim 4, wherein the rinsing liquid is pure water or isopropyl alcohol. The method of claim 5, further comprising a drying step of drying the substrate after the rinsing step. 5. The method according to claim 1, wherein at least one of the step of treating with the oxalic acid aqueous solution, the rinsing step, and the drying step is performed using a single-wafer spin apparatus that rotates one substrate. 7. The method of removing and cleaning a substrate according to any one of 6. The method according to claim 1, wherein the substrate is a substrate for an electro-optical device. A method for manufacturing a substrate for an electro-optical device, comprising a step of treating a layer to be laminated on the substrate for an electro-optical device with an aqueous oxalic acid solution having a concentration of 1 to 10% and a temperature of 30 to 50 ° C.

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