Method of forming semiconductor device

Abstract

A method of forming a semiconductor device includes providing a bit line structure on a substrate, wherein the bit line structure is located between a pair of spacer layers having an air gap; and arranging a silicon nitride film to seal the air gap. Arranging the silicon nitride thin film, wherein a first distance is formed between the spray head and the wafer on the bearing table; providing gas into the operation cavity from the spray head; cleaning the operation cavity; and lifting the spray head to increase the first distance to a second distance. The method of forming the silicon nitride film to seal the air gap can improve the thickness consistency. Therefore, the nitride layer formed on the silicon nitride thin film cannot be filled into the air gap. Therefore, the method can prevent abnormal contours between the unit contacts and the landing pads and avoid wafer test failure.

Description

Technical Field

[0001] The present disclosure relates to a method of forming a semiconductor device. Background Art

[0002] Semiconductor devices are widely used in the electronics industry. Sandwiching a bit line structure in an air gap is a common design in semiconductor devices and is usually used to reduce leakage current. However, the thickness consistency of the film used to seal the air gap is a key factor to prevent the material above the bit line structure from penetrating into the air gap.

[0003] In view of this, how to provide a semiconductor device that can enhance the protection air gap capability is still one of the goals that the industry is working hard to research. Summary of the invention

[0004] One aspect of the present disclosure is a method of forming a semiconductor device.

[0005] In one embodiment of the present disclosure, a method for forming a semiconductor device includes providing a bit line structure on a substrate, wherein the bit line structure is located between a pair of spacer layers having an air gap; and disposing a silicon nitride film to seal the air gap. Disposing the silicon nitride film includes providing gas from a shower head into an operating chamber, wherein a first distance exists between the shower head and a wafer located on a carrier; cleaning the operating chamber; and lifting the shower head so that the first distance increases to a second distance.

[0006] In one embodiment of the present disclosure, before cleaning the operating chamber, the gas pressure in the operating chamber is in the range of 4.5 Torr to 5 Torr.

[0007] In one embodiment of the present disclosure, in the step of lifting the showerhead, the air pressure in the operating chamber is reduced to less than 4.5 Torr.

[0008] In one embodiment of the present disclosure, the gas includes helium and nitrogen, and the ratio between helium and nitrogen is 1:6.

[0009] In one embodiment of the present disclosure, the step of disposing a silicon nitride film to seal the air gap further includes purging gas out of the operating chamber after lifting the shower head.

[0010] In one embodiment of the present disclosure, when the step of lifting the shower head is performed, the gas includes helium and nitrogen.

[0011] In one embodiment of the present disclosure, the method for forming a semiconductor device further includes disposing a first nitride layer on the silicon nitride film.

[0012] In one embodiment of the present disclosure, the method for forming a semiconductor device further includes removing a portion of the silicon nitride film and a portion of the first nitride layer to expose a landing pad disposed on the bit line structure.

[0013] In one embodiment of the present disclosure, the method for forming a semiconductor device further includes forming a cell contact in the second nitride layer disposed on the landing pad.

[0014] Another technical aspect of the present disclosure is a method of forming a semiconductor device.

[0015] In one embodiment of the present disclosure, a method for forming a semiconductor device includes providing a bit line structure on a substrate, wherein the bit line structure is located between a pair of spacer layers having an air gap; and disposing a silicon nitride film to seal the air gap. Disposing the silicon nitride film to seal the air gap includes providing gas from a showerhead into an operating chamber, wherein the showerhead has a first distance from a wafer located on a carrier; cleaning the operating chamber; and increasing the first distance from the showerhead to the wafer to a second distance.

[0016] In one embodiment of the present disclosure, increasing the first distance is performed by lifting the showerhead away from the carrier.

[0017] In one embodiment of the present disclosure, before cleaning the operating chamber, the gas pressure in the operating chamber is in the range of 4.5 Torr to 5 Torr.

[0018] In one embodiment of the present disclosure, in the step of lifting the showerhead, the air pressure in the operating chamber is reduced to less than 4.5 Torr.

[0019] In one embodiment of the present disclosure, the gas includes helium and nitrogen, and the ratio between helium and nitrogen is 1:6.

[0020] In one embodiment of the present disclosure, the step of disposing a silicon nitride film to seal the air gap further includes purging gas out of the operating chamber after lifting the shower head.

[0021] In one embodiment of the present disclosure, when the step of increasing the first distance between the shower head and the wafer is performed, the gas includes helium and nitrogen.

[0022] In the above-mentioned embodiment, the method of forming a silicon nitride film to seal the air gap can improve the thickness uniformity. Thereby, the nitride layer formed on the silicon nitride film will not fill in the air gap. Therefore, this method can prevent the abnormal profile between the cell contact and the landing pad and avoid the wafer acceptance test failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 FIG. 4 is a flow chart of a method for manufacturing a semiconductor device according to an embodiment of the present disclosure.

[0024] Figures 2 to 6 for Figure 1 Cross-sectional views of different stages in a method for manufacturing a semiconductor device.

[0025] Figure 7A flow chart of a method for forming a silicon nitride film.

[0026] Figure 8 Schematic diagram of an operating chamber for semiconductor devices.

[0027] Fig. 9 Schematic diagram of an operating chamber for semiconductor devices. DETAILED DESCRIPTION

[0028] The following will disclose multiple embodiments of the present invention with the accompanying drawings. For the purpose of clear description, many practical details will be described together in the following description. However, it should be understood that these practical details should not be used to limit the present invention. That is, in some embodiments of the present invention, these practical details are not necessary. In addition, in order to simplify the drawings, some conventional structures and elements will be illustrated in the drawings in a simple schematic manner. And for the sake of clarity, the thickness of the layers and regions in the drawings may be exaggerated, and the same element symbols represent the same elements in the description of the drawings.

[0029] Figure 1 1 is a flow chart of a method for manufacturing a semiconductor device 100 according to an embodiment of the present disclosure. The method starts in step S1, providing a bit line structure located on a substrate, and the bit line structure is located between a pair of spacer layers having an air gap. Then, in step S2, a silicon nitride film is disposed to seal the air gap. The next step is step S3, disposing a first nitride layer on the silicon nitride film. Subsequently, in step S4, a portion of the silicon nitride film and a portion of the first nitride layer are removed to expose a landing pad disposed on the bit line structure. Finally, in step S5, a cell contact is formed in the second nitride layer disposed on the landing pad.

[0030] Figures 2 to 6 The cross-sectional views at different stages of the semiconductor device manufacturing method are shown in FIG. Figure 1 and Figure 2 . In step S1, a substrate 110 and a bit line structure 120 located thereon are provided. The bit line structure 120 is sandwiched between a pair of spacer layers 130, and each spacer layer 130 includes an air gap 140. The term "air gap" refers to a cavity filled with air, a gas other than air, or particularly an inert gas such as argon, or may be a vacuum. A landing pad 150 is disposed on the bit line structure 120. In some embodiments, atomic layer deposition (ALD), atomic layer epitaxy (ALE), atomic layer chemical vapor deposition (ALCVD), spin coating, sputtering, etc., can be used to form the landing pad 150 above the bit line structure 120.

[0031] In some embodiments, the bit line structure 120 sequentially includes a bit line contact 122 on the upper surface of the substrate 110 , a tungsten layer 124 on the bit line contact 122 , and a nitride layer 126 on the tungsten layer 124 , but the disclosure is not limited thereto.

[0032] Each bit line structure 120 has an upper surface 120T away from the substrate 110 and a sidewall 120S connected to the upper surface 120T. The landing pad 150 may be disposed on the upper surface 120T of the bit line structure 120 and the spacer layer 130 .

[0033] The upper half of the bit line structure 120 and the upper half of the spacer layer 130 are removed. Therefore, each bit line structure 120 has a recessed surface 128 connecting the upper surface 120T and the sidewall 120S.

[0034] Each landing pad 150 has a first surface 152 connected to the recessed surface 128 of the bit line structure 120. Each landing pad 150 has a second surface 154 facing the recessed surface 128 and an upper surface 156 connecting the first surface 152 and the second surface 154.

[0035] In some embodiments, the recessed surface 128 of the bit line structure 120 is formed when the material in the cavity (the air gap 140) is removed. For example, the material (such as an oxide layer) originally in the cavity is removed by an anisotropic dry etching process or a reactive ion etching process.

[0036] The substrate 110 may be a semiconductor substrate, a base semiconductor layer placed on a support structure, a metal electrode, or a semiconductor substrate on which one or more layers, structures or regions are formed. The substrate 110 may be a semiconductor wafer, such as a silicon wafer. Alternatively, the substrate 110 may include a single semiconductor material, a compound semiconductor material and / or an alloy semiconductor material.

[0037] For example, the alloy semiconductor material may include, but is not limited to, silicon germanium (SiGe), gallium arsenide (GaAsP), aluminum arsenide (AlInAs), aluminum gallium arsenide (AlGaAs), gallium arsenide (GaInAs), gallium phosphide (GaInP) and / or gallium arsenide arsenide (GaInAsP). In some embodiments, the substrate 110 may be a silicon substrate, a gallium arsenide substrate, a silicon germanium substrate, a ceramic substrate, a quartz substrate, a glass substrate, a silicon-on-insulator substrate, etc. In some embodiments, the substrate 110 is a multi-layer structure, including a polysilicon layer and a metal layer sequentially stacked on the substrate.

[0038] Reference Figure 1 and Figure 3. In step S2, a silicon nitride film 160 is formed to seal the air gap 140. Specifically, the silicon nitride film 160 includes a fluorine-resistant etch stop coating (FRESCO). The method of forming the fluorine-resistant etch stop coating and the thickness consistency will be described in detail in the subsequent paragraphs. The silicon nitride film 160 contacts the first surface 152, the second surface 154, the upper surface 156 of the landing pad 150, and the recessed surface 128 of the bit line structure 120. The silicon nitride film 160 is substantially conformal to the contours of the landing pad 150 and the recessed surface 128 of the bit line structure 120. Therefore, the silicon nitride film 160 includes a recessed surface 160S on the recessed surface 128 of the bit line structure 120.

[0039] Reference Figure 1 and Figure 4 In step S3 , a first nitride layer 162 is formed on the silicon nitride film 160 . The first nitride layer 162 is a cap layer formed by an atomic layer deposition process. The silicon nitride film 160 and the first nitride layer 162 are both formed to protect the air gap 140 .

[0040] Reference Figure 1 and Figure 5 In step S4 , a portion of the silicon nitride film 160 and a portion of the first nitride layer 162 are removed by a dry etching process. The upper surface 156 of the landing pad 150 is exposed from the silicon nitride film 160 .

[0041] Reference Figure 1 and Figure 6 In step S5 , the second nitride layer 170 is formed on the landing pad 150 , the silicon nitride film 160 , and the first nitride layer 162 . In a subsequent process, a cell contact 180 is formed on the second nitride layer 170 to contact the landing pad 150 .

[0042] Figure 7 A flow chart of a method 200 for forming a silicon nitride film 160 is provided. Figure 8 A schematic diagram of an operating chamber 300 in which the semiconductor device 100 is placed. Figures 2 to 6 The semiconductor device 100 shown in FIG. Figure 8The wafer 10 is marked in the figure. The operating chamber 300 includes a shower head 310 and a carrier 320. The wafer 10 is placed on the carrier 320. The operating chamber 300 is connected to a heater 330. The shower head 310 is connected to a gas pipeline 340, and the gas used to form the silicon nitride film 160 is provided through the gas pipeline 340. The gas pipeline 340 is connected to a gas transmission system (not shown), including a plurality of gas sources required by the process being operated, etc. For example, precursor gas, reaction gas, cleaning gas, etc. are introduced into the operating chamber 300 through the gas pipeline 340. The operating chamber 300 is connected to a pump 350.

[0043] Reference Figure 7 and Figure 8 . In step 210, a gas is provided for forming the silicon nitride film 160. For example, the gas used to form the silicon nitride film 160 in this step includes a precursor gas, a reaction gas, and a cleaning gas such as monosilane (SiH4), ammonia (NH3), trimethoxysilane (TMS), helium, and nitrogen. The above gases are supplied from the shower head 310 to the operating chamber 300. The deposition process of the silicon nitride film 160 starts after the gas flow is stable. The silicon nitride film 160 is deposited in the landing pad 150, the bit line structure 120, and the cavity in the spacer layer 130. As shown Figure 3 As shown, the air gap 140 is sealed. It should be understood that one or more steps may be included in step 210 according to actual needs.

[0044] In step 210, a first distance L1 is provided between the showerhead 310 and the wafer 10. In some embodiments, the first distance L1 is in the range of 0.25 to 0.6 inches. In step 210, the carrier 320 on which the wafer 10 is disposed is heated to 500 degrees. The pressure in the operating chamber 300 is maintained at 4.5 torr to 5 torr. In a preferred embodiment, the pressure in the operating chamber 300 is maintained at 4.6 torr, which is beneficial to the uniformity of the thin film during the deposition process.

[0045] In step 210, the ratio of helium to nitrogen is 1:6. For example, the gas flow rate of helium is about 3000 sccm (standard milliliters per minute), and the gas flow rate of nitrogen is about 18000 sccm. In this way, compared with the condition without helium, this condition can improve the heat transfer efficiency.

[0046] Reference Figure 7 and Figure 8. In step 220, after depositing the fluorine-resistant etching stop coating, the gas flow supply is cut off and the operating chamber is cleaned. Specifically, the supply of one or more gases among monosilane, ammonia, and trimethoxysilane is gradually or simultaneously stopped. In this step, the pressure of the operating chamber 300 remains substantially the same. The pressure of the operating chamber 300 is reduced to about 2.5 Torr. The ratio between helium and nitrogen is the same as in step 210. The first distance L1 is also the same as in step 210.

[0047] Fig. 9 A schematic diagram of an operating chamber 300 for placing a semiconductor device 100. Figure 7 and Fig. 9 In step 230, the shower head 310 is raised. Fig. 9 As shown, the first distance L1 increases to a second distance L2. In some embodiments, the second distance L2 is approximately 1.7 to 2.1 inches. In a preferred embodiment, the second distance L2 is 1.9 inches.

[0048] In step 230, the uniformity of the deposition process can be improved by increasing the distance between the showerhead 310 and the carrier 320. In this step, the pressure of the operating chamber 300 is maintained at about 2.5 Torr. Figure 4 ) will not penetrate the silicon nitride film 160 and fill the air gap 140. For example, if the consistency of the silicon nitride film 160 is not good, the thickness and profile of the material used to protect the air gap 140 are not stable from the edge to the center of the wafer 10. This will cause the first nitride layer 162 to fill the air gap 140 from the position of the recessed surface 160S of the silicon nitride film 160 and the recessed surface 128 of the bit line structure 120.

[0049] Likewise, in step S5 (see Figure 6 ) will not penetrate the silicon nitride film 160 and the first nitride layer 162 to fill the air gap 140. For example, if the second nitride layer 170 has poor uniformity, the thickness and profile of the material used to protect the air gap 140 will not be stable from the edge to the center of the wafer 10. This will cause the second nitride layer 170 to fill the air gap 140 from the remaining first nitride layer 162, the recessed surface 160S of the silicon nitride film 160, and the recessed surface 128 of the bit line structure 120.

[0050] Therefore, the method of forming the silicon nitride film 160 can prevent an abnormal profile between the cell contact 180 and the landing pad 150. Thus, the electrical performance of the wafer can be improved.

[0051] In step 240, the gas in the operating chamber 300 is evacuated. The gas pressure in the operating chamber 300 is reduced until it becomes a vacuum.

[0052] According to the above-mentioned method 200, the consistency of the silicon nitride film 160 can be improved. For example, in some embodiments, the thickness of the silicon nitride in the conventional method is 150.2 angstroms, and the deviation range of the thickness is about 5.61 angstroms. Therefore, the relationship between the thickness divided by 2 and the thickness divided by the thickness can be obtained to obtain a thickness consistency of about 1.87%. The thickness of the silicon nitride film 160 obtained according to the method 200 is about 146.0 angstroms, and the deviation range of the thickness is about 4.45 angstroms. Therefore, the thickness consistency is reduced to 1.52%, which means that the thickness consistency of the silicon nitride film 160 is improved. Therefore, the method disclosed in the present invention can avoid the failure of the wafer acceptance test.

[0053] In summary, the disclosed method of forming a silicon nitride film to seal an air gap can improve thickness uniformity. Thus, the nitride layer formed on the silicon nitride film will not fill in the air gap. Therefore, this method can prevent abnormal profiles between cell contacts and landing pads and avoid wafer acceptance test failure.

[0054] Although the present invention has been disclosed as above in the form of implementation modes, it is not intended to limit the present invention. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the attached claims.

[0055]

Explanation of symbols

[0056] 10: Wafer

[0057] 100:Semiconductor device

[0058] 110:Substrate

[0059] 120: Bit line structure

[0060] 120S: Sidewall

[0061] 120T: Upper surface

[0062] 122: Bit line contact

[0063] 124: Tungsten layer

[0064] 126: Nitride layer

[0065] 128: Concave surface

[0066] 130: Spacer layer

[0067] 140: Air Gap

[0068] 150: Landing Pad

[0069] 152: First surface

[0070] 154: Second surface

[0071] 156: Upper surface

[0072] 160: Silicon nitride film

[0073] 162: first nitride layer

[0074] 170: second nitride layer

[0075] 180:Unit contact

[0076] 200: Method

[0077] 300: Operation chamber

[0078] 310: Sprinkler head

[0079] 320: Loading platform

[0080] 330: Heater

[0081] 340: Gas pipeline

[0082] 350: Pump

[0083] S1~S5,210~240: Steps

[0084] L1: First distance

[0085] L2: The second distance.

Claims

1. A method for forming a semiconductor device, characterized in that: Include: Providing a bit line structure on a substrate, wherein the bit line structure is located between a pair of spacer layers having an air gap; and Disposing a silicon nitride film to seal the air gap comprises: Provide gas from a shower head into the operating chamber, wherein a first distance exists between the shower head and a wafer on the carrier; cleaning the operating chamber; and Lifting the shower head increases the first distance to a second distance.

2. The method for forming a semiconductor device according to claim 1, wherein: Before cleaning the operating chamber, the gas pressure in the operating chamber is in the range of 4.5 Torr to 5 Torr.

3. The method for forming a semiconductor device according to claim 2, wherein: In the step of lifting the shower head, the air pressure in the operating chamber is reduced to less than 4.5 Torr.

4. The method for forming a semiconductor device according to claim 1, wherein: The gas includes helium and nitrogen, and the ratio of helium to nitrogen is 1:

6.

5. The method for forming a semiconductor device according to claim 1, wherein: The step of disposing the silicon nitride film to seal the air gap further includes purging the gas out of the operating chamber after lifting the shower head.

6. The method for forming a semiconductor device according to claim 1, wherein: When the step of lifting the shower head is performed, the gas includes helium and nitrogen.

7. The method for forming a semiconductor device according to claim 1, wherein: Also includes: A first nitride layer is disposed on the silicon nitride film.

8. The method for forming a semiconductor device according to claim 7, wherein: Also includes: A portion of the silicon nitride film and a portion of the first nitride layer are removed to expose a landing pad disposed on the bit line structure.

9. The method for forming a semiconductor device according to claim 8, wherein: Also includes: An organelle contact is formed in the second nitride layer disposed on the landing pad.

10. A method for forming a semiconductor device, characterized in that: Include: Providing a bit line structure on a substrate, wherein the bit line structure is located between a pair of spacer layers having an air gap; and Disposing a silicon nitride film to seal the air gap comprises: Provide gas from a shower head into the operating chamber, wherein a first distance exists between the shower head and a wafer on the carrier; cleaning the operating chamber; and The first distance between the shower head and the wafer is increased to a second distance.

11. The method for forming a semiconductor device according to claim 10, wherein: The first distance is increased by lifting the shower head away from the carrier.

12. The method for forming a semiconductor device according to claim 10, wherein: Before cleaning the operating chamber, the gas pressure in the operating chamber is in the range of 4.5 Torr to 5 Torr.

13. The method for forming a semiconductor device according to claim 12, wherein: In the step of increasing the first distance between the shower head and the wafer, the gas pressure in the operating chamber is reduced to less than 4.5 Torr.

14. The method for forming a semiconductor device according to claim 10, wherein: The gas includes helium and nitrogen, and the ratio of helium to nitrogen is 1:

6.

15. The method for forming a semiconductor device according to claim 10, wherein: The step of disposing the silicon nitride film to seal the air gap further includes purging the gas out of the operating chamber after increasing the first distance.

16. The method for forming a semiconductor device according to claim 10, wherein: When the step of increasing the first distance between the shower head and the wafer is performed, the gas includes helium and nitrogen.

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