Digital Certificates genereted from Hardware Security Module Software library without hardware based source of entropy will provide enough security to generate digital certificates. However Hardware security Modules provide hardware based source of entropy and apis to generate certificates along with other crypto operations. But buying HSM just for making certificates will be kind of spending much for just one feature. Is there any other way or device to make strong digital certificates?
HSMs are not purchased just for the feature of generating certs.


HSMs also store the certificates very securely. You cannot use the cert in the HSM unless you are authorised   
HSMs also provide very secure management of the HSM itself - for e.g. you can create smart cards for 5 admins &amp; say that atleast any 3 of the cards have to be used to administer the HSM
HSMs provide very high speeds for signing. If you are doing really huge amount signings per second, then this reduces the load on your software.
HSMs also provide high speeds for key generation. This may be important for temporal certificate generation - each certificate is used only for one signing.