JP2002129362A - Method for forming chromium pattern and method for manufacturing liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove a cerium compound which is deposited on a surface, when a chromium layer is etched with an etching solution including cerium salt. SOLUTION: A cerium compound 36 is deposited on the surface, when the chromium layer formed on a n-type amorphous silicon layer 32 is etched with the etching solution using resist patterns 34 and 35 as masks, to form a drain electrode 18 and a source electrode 19 of a thin film transistor as a switching element of a liquid crystal display. Then, this method comprises removing the cerium compound 36 with a post-treatment which employs an acidic solution consisting of nitric acid or hydrofluoric acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a chromium pattern and a method for manufacturing a liquid crystal display.

[0002]

2. Description of the Related Art For example, in an active matrix type liquid crystal display device, a drain electrode and a source electrode of a thin film transistor as a black mask and a switching element are sometimes formed of chromium. For example, when the black mask is formed of chromium, first, as shown in FIG. 9, a chromium layer 2 is formed on the upper surface of the glass substrate 1, and a resist pattern 3 is formed on the upper surface. next,
When the chromium layer 2 is etched using a chromium etching solution containing a cerium salt using the resist pattern 3 as a mask, a black mask 4 made of chromium is formed below the resist pattern 2 as shown in FIG. next,
Water washing for removing the chromium etching solution and drying for removing water are performed. Next, the resist pattern 3 is peeled off.

[0003]

In the above-described conventional method for forming a chromium pattern, the chromium layer 2 is etched using a chromium etching solution containing a cerium salt, washed with water, and dried. As shown in FIG. 11, the surface of the resist pattern 3 and the glass substrate 1
Cerium compound 5 may be deposited on the surface. Since the deposited cerium compound 5 is insoluble in water, it cannot be removed by washing with water.
Is opaque, so that the black mask 4 becomes poor in appearance and becomes a foreign matter at the time of forming a pattern, which may adversely affect a subsequent process. An object of the present invention is to remove a cerium compound deposited on a surface when a chromium layer is etched using a chromium etching solution containing a cerium salt.

[0004]

According to a first aspect of the present invention, there is provided a method for forming a chromium pattern, comprising forming a chromium pattern on a chromium layer using a resist pattern formed on the chromium layer as a mask. After etching using a chromium etching solution, the cerium compound deposited on the surface is removed using an acidic solution. According to a second aspect of the invention, there is provided a method of forming a chromium pattern according to the first aspect, wherein the cerium compound is removed through a water washing and drying step after the etching. According to a third aspect of the present invention, in the method for forming a chromium pattern according to the first aspect, the cerium compound is removed through a water washing step after the etching.
According to a fourth aspect of the invention, there is provided a method of forming a chromium pattern according to the first aspect, wherein a nitric acid solution is used as the acidic solution. According to a fifth aspect of the present invention, there is provided a method of forming a chromium pattern according to the fourth aspect, wherein the nitric acid content of the nitric acid solution is 0.1 to 10 wt%.
According to a sixth aspect of the present invention, there is provided a method of forming a chromium pattern according to the first aspect, wherein a hydrofluoric acid solution is used as the acidic solution. A chromium pattern forming method according to a seventh aspect of the present invention is the method according to the sixth aspect, wherein the hydrofluoric acid solution has a hydrofluoric acid content of 0.01 to 20 wt%. In the method for manufacturing a liquid crystal display device according to the present invention, when forming a chromium pattern on a substrate for a liquid crystal display device, the chromium layer contains a cerium salt using a resist pattern formed thereon as a mask. After etching using a chromium etching solution, the cerium compound deposited on the surface is removed using an acidic solution. According to a ninth aspect of the present invention, there is provided a method of manufacturing a liquid crystal display device according to the eighth aspect, wherein a black mask is formed by the chromium pattern. According to a tenth aspect of the present invention, in the method for manufacturing a liquid crystal display device according to the eighth aspect, a source electrode and a drain electrode of the thin film transistor are formed by the chromium pattern. In the method for manufacturing a liquid crystal display device according to the present invention, when the silicon layer is provided under the chromium layer, a silicon etching solution is used as the acidic solution, and the cerium compound is used. And the silicon layer is etched. According to a twelfth aspect of the present invention, in the method for manufacturing a liquid crystal display device according to the tenth aspect, when an aluminum-based metal layer is provided under the chromium layer, an aluminum-based metal etching solution is used as the acidic solution. In addition, the cerium compound is removed, and the aluminum-based metal layer is etched. According to the first or eighth aspect of the invention, it is possible to remove a cerium compound deposited on the surface when the chromium layer is etched using a chromium etching solution containing a cerium salt.

[0005]

FIG. 1 is a cross-sectional view of a thin film transistor as a switching element of a liquid crystal display device for illustrating a method of forming a chromium pattern according to an embodiment of the present invention. is there. This liquid crystal display device includes a glass substrate 11. A scanning signal line (not shown) including a gate electrode 12 made of an aluminum-based metal film at a predetermined position on the upper surface of the glass substrate 11
Is formed, and a gate insulating film 13 made of silicon nitride is formed on the entire upper surface thereof. A semiconductor thin film 14 made of intrinsic amorphous silicon is formed at a predetermined position on the upper surface of the gate insulating film 13 on the gate electrode 12. A channel protection film 15 made of silicon nitride is formed at a predetermined location on the upper surface of the semiconductor thin film.
An ohmic contact layer 16 made of n-type amorphous silicon is provided on the upper surface of the semiconductor thin film 14 on both sides in the channel length direction on the upper surface of the channel protective film 15 and on both sides thereof.
17 are formed.

A data signal line (not shown) including a drain electrode 18 made of chromium is formed at predetermined locations on the upper surface of one ohmic contact layer 16 and the upper surface of gate insulating film 13, and the other ohmic contact layer 1 is formed.
A source electrode 19 made of chromium is formed on the upper surface of 7, and an overcoat film 20 made of silicon nitride is formed on the entire upper surface. A contact hole 21 is formed in a portion of the overcoat film 20 corresponding to a predetermined portion of the source electrode 19. Overcoat film 2
The pixel electrode 22 made of ITO is provided at a predetermined position on the upper surface of
Are connected to the source electrode 19 through the contact hole 21. Here, the gate electrode 12, the gate insulating film 13, the semiconductor thin film 14, the channel protective film 15,
Ohmic contact layers 16 and 17, drain electrode 18
The source electrode 19 forms a thin film transistor 23.

Next, a method of manufacturing the liquid crystal display device will be described with reference to FIGS. First, as shown in FIG. 2, a scanning signal line (not shown) including a gate electrode 12 made of an aluminum-based metal is formed at a predetermined position on the upper surface of a glass substrate 11. Next, the gate electrode 12
A gate insulating film 13 made of silicon nitride and an intrinsic amorphous silicon layer 31 are formed on the entire upper surface of the glass substrate 11 including the above. Next, a channel protective film 15 made of silicon nitride is formed at a predetermined position on the upper surface of the intrinsic amorphous silicon layer 31 on the gate electrode 12.
Next, the n-type amorphous silicon layer 3 is formed on the entire upper surface of the intrinsic amorphous silicon layer 31 including the channel protective film 15.
2 and a chromium layer 33 are formed. Next, the chrome layer 33
Resist patterns 34 and 35 are formed at predetermined positions on the upper surface of the substrate. In this case, the resist pattern 34 is for forming a data signal line including the drain electrode 18, and the resist pattern 35 is for forming the source electrode 19.

Next, as shown in FIG. 3, when the chromium layer 33 is etched using a chromium etchant containing a cerium salt using the resist patterns 34 and 35 as a mask, the drain electrode 18 made of chromium is formed under the resist pattern 34. Is formed, and a source electrode 19 made of chromium is formed under the resist pattern 35. Next, washing with water for removing the chromium etching solution and drying for removing water are performed.

[0009] Then, as shown in FIG. 4, a cerium compound 36 is deposited on the surfaces of the resist patterns 34 and 35 and the surface of the n-type amorphous silicon layer 32. next,
When the post-treatment is performed using an acidic solution, the cerium compound 36
Is removed (see FIG. 5). In this case, as the acidic solution, a nitric acid solution containing a mixed acid containing nitric acid or diluted nitric acid or a hydrofluoric acid solution containing a mixed acid containing diluted hydrofluoric acid, diluted hydrofluoric acid, ammonium fluoride or the like is used. If the nitric acid content of the nitric acid solution is too small, the ability to remove the cerium compound 36 is reduced, and if it is too large, parts other than the cerium compound 36 are damaged. The hydrofluoric acid content of the hydrofluoric acid solution is desirably 0.01 to 20 wt% for the same reason. Next, washing for removing the acidic solution and drying for removing the water are performed.

Next, as shown in FIG. 5, resist patterns 34 and 35, drain electrode 18 and source electrode 19 are formed.
When the n-type amorphous silicon layer 32 and the intrinsic amorphous silicon layer 31 are dry-etched using such as a mask, one ohmic contact layer 16 is formed below the drain electrode 18 and the other ohmic contact layer is formed below the source electrode 19, as shown in FIG. An ohmic contact layer 17 is formed. Further, a semiconductor thin film 14 is formed under both the ohmic contact layers 16 and 17 and under the channel protective film 15. Next, the resist patterns 34 and 35 are removed.

Next, as shown in FIG. 1, an overcoat film 20 made of silicon nitride is formed on the entire upper surface of the gate insulating film 12 including the thin film transistor 23 and the like. Next, a contact hole 21 is formed in a portion of the overcoat film 20 corresponding to a predetermined portion of the source electrode 19.
Next, IT is applied to a predetermined portion of the upper surface of the overcoat film 20.
The pixel electrode 22 made of O is connected to the source electrode 19 through the contact hole 21 and formed.

In the liquid crystal display device obtained as described above, as described above, the cerium compound 3 is obtained by performing post-treatment using an acidic solution in the step shown in FIG.
Since 6 is removed, the appearance of the data signal line including the drain electrode 18 and the source electrode 19 can be prevented. Further, the cerium compound 36 does not adversely affect the subsequent steps. In this embodiment, the n-type amorphous silicon layer 32 and the intrinsic amorphous silicon layer 32 are formed by using the resist patterns 34 and 35, the drain electrode 18 and the source electrode 19 as a mask. 3
When dry-etching 1, it is possible to prevent the etching from taking a long time and causing processing defects.

In the above embodiment, it has been described that the cerium compound 36 is deposited when the chromium layer 33 is etched by using a chromium etching solution, and is subjected to a water washing and drying process. However, the cerium compound 36 is actually deposited. Occurs when the chromium etchant attached to the surfaces of the resist patterns 34 and 35 and the surface of the n-type amorphous silicon layer 32 is appropriately diluted with water. Therefore, the deposited cerium compound 36 may be removed using an acidic solution from the point of occurrence and before the above-mentioned drying step, and washing with water for removing the acidic solution may be performed. In this case, the number of washing and drying steps can be reduced as compared with the above embodiment.

In the above embodiment, when the n-type amorphous silicon layer 32 and the intrinsic amorphous silicon layer 31 are wet-etched, if the silicon etchant used at that time is a hydrofluoric acid solution, as shown in FIG. The n-type amorphous silicon layer 32 and the intrinsic amorphous silicon layer 31 may be etched while removing the cerium compound 36 with a hydrofluoric acid solution.

In the above embodiment, the drain electrode 1
Although the case where the data signal line including 8 and the source electrode 19 have a single-layer structure of a chromium layer has been described, the present invention is not limited to this, and a two-layer structure of an aluminum-based metal layer and a chromium layer may be used. In this case, in a step corresponding to the step shown in FIG. 4, since the aluminum-based metal layer 41 is formed on the n-type amorphous silicon layer 32 as shown in FIG. The aluminum-based metal layer 41 is etched using the mask 18 and the source electrode 19 as a mask. If the aluminum-based metal etchant used at this time is a nitric acid solution, the cerium compound 36 is removed with the nitric acid solution. Alternatively, the aluminum-based metal layer 41 may be etched.

Further, in the above embodiment, the case where the data signal line including the drain electrode 18 and the source electrode 19 are formed of chromium has been described. Can be applied. Further, the present invention is not limited to the above-described chrome pattern of the liquid crystal display device, and can be applied to a chrome pattern of another device.

[0017]

As described above, according to the present invention, when a chromium layer is etched using a chromium etching solution containing a cerium salt, a cerium compound deposited on the surface can be removed. The appearance of the pattern can be prevented from being poor, and the cerium compound can be prevented from adversely affecting the subsequent steps.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a thin film transistor as a switching element of a liquid crystal display device for illustrating a method of forming a chromium pattern according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an initial step in manufacturing the liquid crystal display device shown in FIG.

FIG. 3 is a sectional view showing a step following FIG. 2;

FIG. 4 is a sectional view showing a step following FIG. 3;

FIG. 5 is a sectional view showing a step following FIG. 4;

FIG. 6 is a sectional view showing a step following FIG. 5;

FIG. 7 is a sectional view for explaining another embodiment of the present invention.

FIG. 8 is a cross-sectional view for explaining still another embodiment of the present invention.

FIG. 9 is a cross-sectional view showing an initial step in forming a black mask made of chromium in a conventional liquid crystal display device.

FIG. 10 is a sectional view showing a step following FIG. 9;

FIG. 11 is a sectional view for explaining a conventional problem.

DESCRIPTION OF SYMBOLS 11 Glass substrate 12 Gate electrode 13 Gate insulating film 14 Semiconductor thin film 15 Channel protective film 16, 17 Ohmic contact layer 18 Drain electrode 19 Source electrode 20 Overcoat film 22 Pixel electrode 23 Thin film transistor 31 Intrinsic amorphous silicon layer 32 n Type amorphous silicon layer 33 chrome layer 34, 35 resist pattern

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/304 647 G02F 1/136 500 5F043 21/306 H01L 21/306 F 5F110 21/3213 21/88 C 21/3205 M 29/786 29/78 616K 21/336 627C F-term (reference) 2H091 FA35Y FC02 FC10 FC26 FD04 FD12 FD22 GA13 LA11 LA12 2H092 JA26 JA29 JA38 JA42 JA44 JA47 JB13 JB23 JB32 JB33 JB37 JB51 KA07 KA05 MA05 MA08 MA14 MA15 MA16 MA18 MA19 MA20 MA27 MA35 MA37 MA41 NA25 NA27 NA29 PA09 4K057 WA01 WA20 WB05 WB06 WB08 WE02 WE07 WG10 WK01 WN01 WN02 4M104 AA09 BB01 BB40 CC01 DD64 FF13 GG09 HH04 H05Q04 H0420H04H05H04H04H04 AA26 BB18 BB27 BB30 DD12 GG02 5F110 AA26 AA30 CC07 DD02 EE03 FF03 GG02 GG15 GG35 HK04 HK09 HK16 HK21 HK42 NN02 NN12 NN24 NN72 QQ05

Claims (12)

[Claims] When forming a chromium pattern, a chromium layer is etched using a chromium etching solution containing a cerium salt using a resist pattern formed thereon as a mask, and then a cerium compound deposited on the surface is acidified. A method for forming a chromium pattern, wherein the chromium pattern is removed by using chromium. 2. The method according to claim 1, wherein the cerium compound is removed through a washing and drying process after the etching. 3. The method according to claim 1, wherein the cerium compound is removed through a water washing step after the etching. 4. The method according to claim 1, wherein a nitric acid solution is used as the acidic solution. 5. The method according to claim 4, wherein the nitric acid content of the nitric acid solution is 0.1 to 10% by weight. 6. The method according to claim 1, wherein a hydrofluoric acid solution is used as the acidic solution. 7. The method according to claim 6, wherein the hydrofluoric acid solution has a hydrofluoric acid content of 0.01 to 20 wt%. 8. When forming a chromium pattern on a substrate for a liquid crystal display device, the chromium layer is etched using a chromium etching solution containing a cerium salt using the resist pattern formed thereon as a mask, and then the surface is etched. A method for manufacturing a liquid crystal display device, comprising removing a cerium compound deposited on a substrate using an acidic solution. 9. The method according to claim 8, wherein the chrome pattern is a black mask. 10. The method according to claim 8, wherein the chromium pattern is a source electrode and a drain electrode of a thin film transistor. 11. The invention according to claim 10, wherein when a silicon layer is provided under the chromium layer, the silicon layer is etched while removing the cerium compound using a silicon etching solution as the acidic solution. A method for manufacturing a liquid crystal display device, comprising: 12. The method according to claim 10, wherein when an aluminum-based metal layer is provided under the chromium layer, the cerium compound is removed by using an aluminum-based metal etching solution as the acidic solution, and the aluminum-based metal layer is removed. A method for manufacturing a liquid crystal display device, characterized by etching a metal layer.