Background technology
Along with the continuous progress of ic manufacturing process, the continuous reduction of live width, the layout of semi-conductor, also from common simple function discrete device, develops into the unicircuit integrating high-density multifunction.
In semiconductor fabrication process, photoetching is one of them extremely important step. Photoetching process is that the pattern on mask plate is copied crystal column surface, and its detailed process is: adopt spin coating proceeding to form photoresist layer on wafer; Being heat-treated by this photoresist layer is placed in exposure sources, is exposed to described photoresist layer by exposure technology, by the design transfer on mask plate in photoresist layer; Then the photoresist layer after exposure is carried out post-exposure heat process, and developed by developing process, form photoengraving pattern in the photoresist.
When adopting spin coating proceeding to form photoresist layer on wafer, it is easy to form the residual of photoresist material material at crystal round fringes and the back side, the residual of photoresist material material can stain equipment, affects follow-up exposure technology, brings the defect of particle.
In order to overcome the problems referred to above, the method that the method (WEE, WaferEdgeExposure) of the method (EBR, EdgeBeadRemoval) that existing usual employing edge removes photoresist and edge exposure combines removes crystal round fringes and the residual of back side formation photoresist material material.
Wherein, the method (EBR) that edge removes photoresist is: when adopting spin coating proceeding to form photoresist layer on wafer, adopt the photoresist material material going limit solvent to remove crystal round fringes and the back side. the method (WEE) of edge exposure is: adopt laser to be exposed by the photoresist material material of crystal round fringes, and the photoresist material material that crystal round fringes is exposed is removed when developing. the method of edge exposure has higher precision and good edge shape looks compared to the method that edge removes photoresist, along with node technology develops to submicron direction, adopt the method (EBR that edge removes photoresist, and the method (WEE of edge exposure EdgeBeadRemoval), WaferEdgeExposure) method combined removes the residual of crystal round fringes and back side formation photoresist material material with in the making processes being widely used in semi-conductor, but the photoresist layer adopting aforesaid method process easily forms defect at edge, when forming deep trench by mask etching wafer of described photoresist layer, the defect of silicon grain is easily formed at edge.
More forming methods about photoresist layer please refer to the Chinese patent that publication number is CN102169292A.
Summary of the invention
The problem that the present invention solves is to provide the forming method of photoresist layer in a kind of deep trench processes, reduces the defect of crystal round fringes photoresist layer.
For solving the problem, the forming method of photoresist layer in a kind of deep trench processes of the present invention, it is characterised in that, comprising:
Wafer is provided;
Adopting spin coating proceeding to form photoresist layer on described wafer, adopt the photoresist layer going limit solvent to remove wafer edge portion width simultaneously, the removal width of described photoresist layer is 1.7 ~ 1.9 millimeters;
Described photoresist layer is exposed and developing process forms patterned photoresist layer.
Optionally, the flow range removing limit solvent described in is 10 ~ 20 ml/min.
Optionally, when the photoresist layer that wafer edge portion width removed by limit solvent is removed in described employing, the injection direction line of limit solvent and the angular range of crystal column surface is gone to be 40 ~ 60 degree.
Optionally, go the projection line of the injection direction line of limit solvent on wafer parallel with the tangent line at the edge of wafer described in.
Optionally, the material of described photoresist layer is deep ultraviolet light-sensitive lacquer.
Optionally, described photoresist layer thickness is 4500 ~ 5500 dusts.
Optionally, during described spin coating proceeding, the temperature of room, chamber is 21 ~ 23 degree, and relative humidity is 40% ~ 50%.
Optionally, during described spin coating proceeding, the pressure of the lower air draft of room, chamber is 40 ~ 60 handkerchiefs.
Optionally, limit solvent is gone to be organic solvent described in.
Optionally, after adopting spin coating proceeding to form photoresist layer, also comprise: described wafer is carried out gluing postheat treatment.
Optionally, the temperature of described gluing postheat treatment is 70 ~ 180 degrees Celsius, and the time is 20 ~ 200 seconds.
Optionally, also comprise: taking described patterned photoresist layer as mask, etch described wafer, form deep trench.
Compared with prior art, technical solution of the present invention has the following advantages:
After adopting the photoresist layer removing limit solvent removal wafer edge portion width, the photoresist layer to crystal round fringes is not needed to carry out the process of edge exposure, avoid the phenomenon that light leak occurs, improve the homogeneity of the thickness of the photoresist layer of crystal round fringes, the removal width of described photoresist layer is 1.7 ~ 1.9 millimeters, while removing the not good part photoresist material of edge homogeneity, ensure that the utilization ratio of wafer.
The described flow range removing limit solvent is 10 ~ 20 ml/min, the injection direction line of limit solvent and the angular range of crystal column surface is gone to be 40 ~ 60 degree, and described in go the projection line of the injection direction line of limit solvent on wafer parallel with the tangent line at the edge of wafer, limit solvent is gone to be that the oblique tangent photoresist material material with photoresist layer contacts, reduce limit solvent to the surging force of photoresist material material, reduce photoresist material material in sense of rotation to the resistance removing limit solution, the photoresist material edge after removal part width is made to have good shape looks, and remove process can not cause and crossing of photoresist layer edge is removed, the edge thickness of the photoresist layer after removal part width is made to keep homogeneity, follow-up needs adopts edge exposure technique to be revised at the edge of photoresist layer, avoid the generation of light leakage phenomena, save processing step.
Embodiment
Contriver finds in the technique that existing employing photoresist layer is mask formation deep trench, and easily produce the defect of silicon grain at the edge of wafer, the semiconducter device that follow-up process apparatus and wafer are formed very easily is caused contamination by these silicon grains produced.
Contriver finds through research, the homogeneity of the thickness at the photoresist layer edge that existing technique is formed is poor, make the photoresist material figure of crystal round fringes cross thin or distortion when graphical photoresist layer, when forming deep trench by mask etching wafer substrate of patterned photoresist layer, easily form the defect of silicon grain at the edge of wafer. Contriver studies discovery further, the homogeneity of the thickness at the edge of the photoresist layer that spin coating proceeding is formed on wafer to be differed from the homogeneity of the thickness in region intermediate, and the method that existing edge removes photoresist is the photoresist material adopting organic solvent to remove edge, when adopting the photoresist material that organic solvent removes edge, due to the impact injecting the factor such as angle, flow of organic solvent, the crossing of edge bead layer of wafer can be caused to remove, affect thickness and the shape looks of the photoresist layer of crystal round fringes; The method of edge exposure is when exposing the photoresist layer of crystal round fringes, the phenomenon of light leak easily occurs, that causes the photoresist layer to crystal round fringes crosses exposure, affect thickness and the shape looks of the photoresist layer of crystal round fringes, in deep trench processes, during using photoresist layer as mask layer, owing to the thickness of photoresist layer and the shape looks at edge there occurs bigger change, when forming deep trench in the edge section of wafer, the loss of photoresist layer is bigger, and as normal mask, can not can form the defect of silicon grain at crystal round fringes.
For solving the problem, contriver proposes the forming method of photoresist layer in deep trench processes, after adopting the photoresist layer removing limit solvent removal wafer edge portion width, the photoresist layer to crystal round fringes is not needed to carry out the process of edge exposure, avoiding phenomenon light leak occur, it is to increase the homogeneity of the thickness of the photoresist layer of crystal round fringes, the removal width of described photoresist layer is 1.7 ~ 1.9 millimeters, while removing the not good part photoresist material of edge homogeneity, ensure that the utilization ratio of wafer.
For enabling above-mentioned purpose, the feature and advantage of the present invention more become apparent, below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in detail.
With reference to the schematic flow sheet that figure 1, Fig. 1 is the forming method of photoresist layer in embodiment of the present invention deep trench processes, comprising:
Step S201, it is provided that wafer;
Step S202, adopts spin coating proceeding to form photoresist layer on described wafer, adopts the photoresist layer going limit solvent to remove wafer edge portion width simultaneously, and the removal width of described photoresist layer is 1.7 ~ 1.9 millimeters;
Step S203, exposes described photoresist layer and developing process forms patterned photoresist layer.
Fig. 2 ~ Fig. 4 is the structural representation of the forming process of photoresist layer in embodiment of the present invention deep trench processes, and Fig. 4 is the cross-sectional view of Fig. 3 along line of cut a-b direction.
With reference to figure 2, it is provided that wafer 300.
The material of described wafer 300 is silicon single crystal, and the size of described wafer 300 is more than or equal to 8 inches.
With reference to figure 3 and Fig. 4, adopting spin coating proceeding to form photoresist layer 301, adopt the photoresist layer 301 going limit solvent to remove wafer 300 edge section width simultaneously on described wafer 300, the removal width of described photoresist layer 301 is 1.7 ~ 1.9 millimeters.
Described spin coating proceeding carries out in room, gluing chamber, and in gluing process, photoresist material shower nozzle 10 from photoresist material is sprayed onto on wafer 300 center surface of rotation, and photoresist material is coated to full wafer wafer 300 surface under the influence of centrifugal force.
The material of described photoresist layer 301 is deep ultraviolet (DeepUltraviolet, DUV) photoresist material, comprises the deep ultraviolet light-sensitive lacquer of 193 nanometers and 248nm nanometer. When exposing, deep ultraviolet (DeepUltraviolet, DUV) photoresist material can issue biochemical reaction in the irradiation of deep UV (ultraviolet light), and according to the different qualities of photoresist material, illuminated photoresist material is removed by developing solution when developing or is not removed.
When forming photoresist layer 301, under the humiture of the homogeneity of the thickness of photoresist layer 301 and the thickness of photoresist layer, room, gluing chamber and room, gluing chamber, the pressure and other parameters of air draft is relevant, and when the material of photoresist layer 301 is different, corresponding parameter can be distinct.
In the embodiment of the present invention, the thickness of described photoresist layer 301 is 4500 ~ 5500 dusts, follow-up taking photoresist layer be grinding form deep trench time, ensure that the thickness of photoresist layer 301 meets the requirement of technique. When forming photoresist layer 301, during described spin coating proceeding, the temperature of room, chamber is 21 ~ 23 degree, relative humidity is 40% ~ 50%, photoresist layer 301 entirety of formation is made to have good homogeneity, during described spin coating proceeding, the pressure of the lower air draft of room, chamber is 40 ~ 60 handkerchiefs, makes the thickness at photoresist layer 301 edge of formation suitable with middle thickness, can not be too thick or too thin, when the photoresist material of the part width at follow-up removal edge, make the shape looks that the edge of photoresist layer keeps good.
After wafer 300 applies a layer photoetching glue-line 301, in order to prevent the photoresist material material at edge to the contamination of equipment, adopt the photoresist layer 301 going limit solvent to remove wafer 300 edge section width. Described limit solution is gone to be organic solution, crack approach is gone also to carry out in gluing chamber, after photoresist material coated materials crystal column surface, arranging the limit solvent shower nozzle ejection of going with side, gluing chamber goes limit solvent on the photoresist material material of crystal round fringes, remove the photoresist material material of limit dissolution with solvents crystal round fringes, by the material after dissolving along with the rotation of wafer throws away crystal column surface. The removal width c of described photoresist layer 301 is 1.7 ~ 1.9 millimeters, while removing the not good photoresist material material of edge homogeneity, ensure the utilization ratio of wafer, namely semiconducter device can not be formed in the region of 1.7 ~ 1.9 mm in width at distance wafer 300 edge, if the width removed is more wide, the utilization ratio of wafer is more low, if the width removed is less, crack approach can be made to be difficult to control, make finally the shape looks at the edge of the photoresist layer 301 of formation and the homogeneity of thickness poor, when follow-up formation deep trench, form silicon grain defect at the edge of wafer.
Described limit solution is gone to be organic solvent, when going to limit, the described flow range removing limit solvent is 10 ~ 20 ml/min, the injection direction line of limit solvent and angle 22 scope of crystal column surface is gone to be 40 ~ 60 degree, the injection direction of limit solvent and the sense of rotation of wafer is gone to be in the same way, described go the projection line 21 of the injection direction line of limit solvent on wafer parallel with the tangent line at the edge of wafer, limit solvent is gone to be that the oblique tangent photoresist material material with photoresist layer 301 contacts, reduce limit solvent to the surging force of photoresist material material, reduce photoresist material material in sense of rotation to the resistance removing limit solution, the photoresist material edge after removal part width is made to have good shape looks, and remove process can not cause and crossing of photoresist layer 301 edge is removed, the edge thickness of the photoresist layer 301 after removal part width is made to keep homogeneity, follow-up needs adopts edge exposure technique to be revised at the edge of photoresist layer 301, avoid the generation of light leakage phenomena, save processing step. it should be noted that, described angle 22 is for removing the angle between the injection direction line 20 of limit solvent and injection direction line 20 projection line 21 on wafer, and described tangent line is be perpendicular to through the wafer center of circle and the straight line removing ray between the spray site of limit solvent on wafer.
After adopting spin coating proceeding to form photoresist layer 301, described wafer is carried out gluing postheat treatment, remove the partial solvent in photoresist layer 301, after carrying out gluing postheat treatment, carry out corresponding cooling process.
The temperature of described gluing postheat treatment is 70 ~ 180 degrees Celsius, and the time is 20 ~ 200 seconds.
Then, described photoresist layer 301 is exposed and developing process forms patterned photoresist layer. Owing to the edge of the photoresist layer 301 of aforesaid method formation has good thickness evenness and edge shape looks, therefore form patterned photoresist layer through exposure and developing process crystal round fringes and there are good thickness evenness and edge shape looks, there will not be the situation that thickness is too thin or shape looks are not good, when the follow-up substrate taking patterned photoresist layer as mask etching wafer forms deep trench, the patterned photoresist layer of crystal round fringes has good mask effect, can not form the defect of silicon grain at the edge of wafer.
After forming patterned photoresist layer, also comprise: taking described patterned photoresist layer as mask, etch described wafer, form deep trench. The degree of depth of described deep trench is greater than 1 micron.
Owing to the edge of photoresist layer patterned on wafer 300 has good thickness evenness and shape looks, in etching process, the photoresist layer of crystal round fringes there will not be over etching or the phenomenon such as collapse, the substrate of the wafer at edge normally etches, when forming deep trench, there will not be the defect of silicon grain at the edge of wafer.
To sum up, the forming method of photoresist layer in the deep trench processes that the embodiment of the present invention provides, after adopting the photoresist layer removing limit solvent removal wafer edge portion width, the photoresist layer to crystal round fringes is not needed to carry out the process of edge exposure, avoiding phenomenon light leak occur, it is to increase the homogeneity of the thickness of the photoresist layer of crystal round fringes, the removal width of described photoresist layer is 1.7 ~ 1.9 millimeters, while removing the not good part photoresist material of edge homogeneity, ensure that the utilization ratio of wafer.
The described flow range removing limit solvent is 10 ~ 20 ml/min, the injection direction line of limit solvent and the angular range of crystal column surface is gone to be 40 ~ 60 degree, and described in go the projection line of the injection direction line of limit solvent on wafer parallel with the tangent line at the edge of wafer, limit solvent is gone to be that the oblique tangent photoresist material material with photoresist layer contacts, reduce limit solvent to the surging force of photoresist material material, reduce photoresist material material in sense of rotation to the resistance removing limit solution, the photoresist material edge after removal part width is made to have good shape looks, and remove process can not cause and crossing of photoresist layer edge is removed, the edge thickness of the photoresist layer after removal part width is made to keep homogeneity, follow-up needs adopts edge exposure technique to be revised at the edge of photoresist layer, avoid the generation of light leakage phenomena, save processing step.
Although the present invention is with better embodiment openly as above; but it is not for limiting the present invention; any those skilled in the art are without departing from the spirit and scope of the present invention; can utilize the Method and Technology content of above-mentioned announcement that technical solution of the present invention is made possible variation and amendment; therefore; every content not departing from technical solution of the present invention; any simple modification, equivalent variations and the modification above embodiment done according to the technical spirit of the present invention, all belongs to the protection domain of technical solution of the present invention.